Handover in Unlicensed Band

ABSTRACT

A wireless device receives a radio resource control message from a base station that indicates a handover from a first cell of the first base station to a second cell of a second base station. During the handover, a DCI from the second base station is received that indicates a random access channel occasion. The random access channel occasion is determined and used to transmit a preamble to the second base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/800,518, filed Feb. 25, 2020, which claims the benefit of U.S.Provisional Application No. 62/818,345, filed Mar. 14, 2019, all ofwhich are hereby incorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosureare described herein with reference to the drawings.

FIG. 1 is a diagram of an example RAN architecture as per an aspect ofan embodiment of the present disclosure.

FIG. 2A is a diagram of an example user plane protocol stack as per anaspect of an embodiment of the present disclosure.

FIG. 2B is a diagram of an example control plane protocol stack as peran aspect of an embodiment of the present disclosure.

FIG. 3 is a diagram of an example wireless device and two base stationsas per an aspect of an embodiment of the present disclosure.

FIG. 4A, FIG. 4B, FIG. 4C and FIG. 4D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure.

FIG. 5A is a diagram of an example uplink channel mapping and exampleuplink physical signals as per an aspect of an embodiment of the presentdisclosure.

FIG. 5B is a diagram of an example downlink channel mapping and exampledownlink physical signals as per an aspect of an embodiment of thepresent disclosure.

FIG. 6 is a diagram depicting an example frame structure as per anaspect of an embodiment of the present disclosure.

FIG. 7A and FIG. 7B are diagrams depicting example sets of OFDMsubcarriers as per an aspect of an embodiment of the present disclosure.

FIG. 8 is a diagram depicting example OFDM radio resources as per anaspect of an embodiment of the present disclosure.

FIG. 9A is a diagram depicting an example CSI-RS and/or SS blocktransmission in a multi-beam system.

FIG. 9B is a diagram depicting an example downlink beam managementprocedure as per an aspect of an embodiment of the present disclosure.

FIG. 10 is an example diagram of configured BWPs as per an aspect of anembodiment of the present disclosure.

FIG. 11A and FIG. 11B are diagrams of an example multi connectivity asper an aspect of an embodiment of the present disclosure.

FIG. 12 is a diagram of an example random access procedure as per anaspect of an embodiment of the present disclosure.

FIG. 13 is a structure of example MAC entities as per an aspect of anembodiment of the present disclosure.

FIG. 14 is a diagram of an example RAN architecture as per an aspect ofan embodiment of the present disclosure.

FIG. 15 is a diagram of example RRC states as per an aspect of anembodiment of the present disclosure.

FIG. 16 is a diagram of example handover procedure as per an aspect ofan embodiment of the present disclosure.

FIG. 17 is a diagram of example cell and/or beam measurements as per anaspect of an embodiment of the present disclosure.

FIG. 18 is a diagram of example beam-based measurement model as per anaspect of an embodiment of the present disclosure.

FIG. 19 is a diagram of example signaling for handover procedure withdynamic PRACH scheduling as per an aspect of an embodiment of thepresent disclosure.

FIG. 20 is a diagram of example signaling for random access proceduretriggered by a handover with dynamic PRACH scheduling as per an aspectof an embodiment of the present disclosure.

FIG. 21 is a diagram of example dynamic PRACH scheduling for handoverprocedure as per an aspect of an embodiment of the present disclosure.

FIG. 22 is a diagram of example monitoring steps for handover procedurewith dynamic PRACH scheduling as per an aspect of an embodiment of thepresent disclosure.

FIG. 23 is a diagram of example monitoring for receiving a PRACH triggersignal (DCI) as per an aspect of an embodiment of the presentdisclosure.

FIG. 24 is a diagram of example dynamic resource allocation for PRACH asper an aspect of an embodiment of the present disclosure.

FIG. 25 is a diagram of example procedure for monitoring and receiving adynamic PRACH trigger signal followed by determining a dynamicallyscheduled RACH occasion as per an aspect of an embodiment of the presentdisclosure.

FIG. 26 is a flow diagram of an example embodiment for a wireless devicescheduled with dynamic random access channel resources during a handoverin unlicensed bands as per an aspect of the present disclosure.

FIG. 27 is a flow diagram of an example embodiment for a base stationdynamically scheduling random access channel resources during a handoverin unlicensed bands as per an aspect of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present disclosure enable operation ofhandover in unlicensed band. Embodiments of the technology disclosedherein may be employed in the technical field of multicarriercommunication systems. More particularly, the embodiments of thetechnology disclosed herein may relate to dynamic scheduling of randomaccess for handover in unlicensed band in a multicarrier communicationsystem.

The following Acronyms are used throughout the present disclosure:

3GPP 3rd Generation Partnership Project

5GC 5G Core Network

ACK Acknowledgement

AMF Access and Mobility Management Function

ARQ Automatic Repeat Request

AS Access Stratum

ASIC Application-Specific Integrated Circuit

BA Bandwidth Adaptation

BCCH Broadcast Control Channel

BCH Broadcast Channel

BPSK Binary Phase Shift Keying

BWP Bandwidth Part

CA Carrier Aggregation

CC Component Carrier

CCCH Common Control CHannel

CDMA Code Division Multiple Access

CN Core Network

CP Cyclic Prefix

CP-OFDM Cyclic Prefix-Orthogonal Frequency Division Multiplex

C-RNTI Cell-Radio Network Temporary Identifier

CS Configured Scheduling

CSI Channel State Information

CSI-RS Channel State Information-Reference Signal

CQI Channel Quality Indicator

CSS Common Search Space

CU Central Unit

DC Dual Connectivity

DCCH Dedicated Control CHannel

DCI Downlink Control Information

DL Downlink

DL-SCH Downlink Shared CHannel

DM-RS DeModulation Reference Signal

DRB Data Radio Bearer

DRX Discontinuous Reception

DTCH Dedicated Traffic CHannel

DU Distributed Unit

EPC Evolved Packet Core

E-UTRA Evolved UMTS Terrestrial Radio Access

E-UTRAN Evolved-Universal Terrestrial Radio Access Network

FDD Frequency Division Duplex

FPGA Field Programmable Gate Arrays

F1-C F1-Control plane

F1-U F1-User plane

gNB next generation Node B

HARQ Hybrid Automatic Repeat reQuest

HDL Hardware Description Languages

IE Information Element

IP Internet Protocol

LCID Logical Channel IDentifier

LTE Long Term Evolution

MAC Media Access Control

MCG Master Cell Group

MCS Modulation and Coding Scheme

MeNB Master evolved Node B

MIB Master Information Block

MME Mobility Management Entity

MN Master Node

NACK Negative Acknowledgement

NAS Non-Access Stratum

NG CP Next Generation Control Plane

NGC Next Generation Core

NG-C NG-Control plane

ng-eNB next generation evolved Node B

NG-U NG-User plane

NR New Radio

NR MAC New Radio MAC

NR PDCP New Radio PDCP

NR PHY New Radio PHYsical

NR RLC New Radio RLC

NR RRC New Radio RRC

NSSAI Network Slice Selection Assistance Information

O&M Operation and Maintenance

OFDM Orthogonal Frequency Division Multiplexing

PBCH Physical Broadcast CHannel

PCC Primary Component Carrier

PCCH Paging Control CHannel

PCell Primary Cell

PCH Paging CHannel

PDCCH Physical Downlink Control CHannel

PDCP Packet Data Convergence Protocol

PDSCH Physical Downlink Shared CHannel

PDU Protocol Data Unit

PHICH Physical HARQ Indicator CHannel

PHY PHYsical

PLMN Public Land Mobile Network

PMI Precoding Matrix Indicator

PRACH Physical Random Access CHannel

PRB Physical Resource Block

PSCell Primary Secondary Cell

PSS Primary Synchronization Signal

pTAG primary Timing Advance Group

PT-RS Phase Tracking Reference Signal

PUCCH Physical Uplink Control CHannel

PUSCH Physical Uplink Shared CHannel

QAM Quadrature Amplitude Modulation

QFI Quality of Service Indicator

QoS Quality of Service

QPSK Quadrature Phase Shift Keying

RA Random Access

RACH Random Access CHannel

RAN Radio Access Network

RAT Radio Access Technology

RA-RNTI Random Access-Radio Network Temporary Identifier

RB Resource Blocks

RBG Resource Block Groups

RI Rank Indicator

RLC Radio Link Control

RRC Radio Resource Control

RS Reference Signal

RSRP Reference Signal Received Power

SCC Secondary Component Carrier

SCell Secondary Cell

SCG Secondary Cell Group

SC-FDMA Single Carrier-Frequency Division Multiple Access

SDAP Service Data Adaptation Protocol

SDU Service Data Unit

SeNB Secondary evolved Node B

SFN System Frame Number

S-GW Serving GateWay

SI System Information

SIB System Information Block

SMF Session Management Function

SN Secondary Node

SpCell Special Cell

SRB Signaling Radio Bearer

SRS Sounding Reference Signal

SS Synchronization Signal

SSS Secondary Synchronization Signal

sTAG secondary Timing Advance Group

TA Timing Advance

TAG Timing Advance Group

TAI Tracking Area Identifier

TAT Time Alignment Timer

TB Transport Block

TC-RNTI Temporary Cell-Radio Network Temporary Identifier

TDD Time Division Duplex

TDMA Time Division Multiple Access

TTI Transmission Time Interval

UCI Uplink Control Information

UE User Equipment

UL Uplink

UL-SCH Uplink Shared CHannel

UPF User Plane Function

UPGW User Plane Gateway

VHDL VHSIC Hardware Description Language

Xn-C Xn-Control plane

Xn-U Xn-User plane

Example embodiments of the disclosure may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CodeDivision Multiple Access (CDMA), Orthogonal Frequency Division MultipleAccess (OFDMA), Time Division Multiple Access (TDMA), Wavelettechnologies, and/or the like. Hybrid transmission mechanisms such asTDMA/CDMA, and OFDM/CDMA may also be employed. Various modulationschemes may be applied for signal transmission in the physical layer.Examples of modulation schemes include, but are not limited to: phase,amplitude, code, a combination of these, and/or the like. An exampleradio transmission method may implement Quadrature Amplitude Modulation(QAM) using Binary Phase Shift Keying (BPSK), Quadrature Phase ShiftKeying (QPSK), 16-QAM, 64-QAM, 256-QAM, and/or the like. Physical radiotransmission may be enhanced by dynamically or semi-dynamically changingthe modulation and coding scheme depending on transmission requirementsand radio conditions.

FIG. 1 is an example Radio Access Network (RAN) architecture as per anaspect of an embodiment of the present disclosure. As illustrated inthis example, a RAN node may be a next generation Node B (gNB) (e.g.120A, 120B) providing New Radio (NR) user plane and control planeprotocol terminations towards a first wireless device (e.g. 110A). In anexample, a RAN node may be a next generation evolved Node B (ng-eNB)(e.g. 120C, 120D), providing Evolved UMTS Terrestrial Radio Access(E-UTRA) user plane and control plane protocol terminations towards asecond wireless device (e.g. 110B). The first wireless device maycommunicate with a gNB over a Uu interface. The second wireless devicemay communicate with a ng-eNB over a Uu interface.

A gNB or an ng-eNB may host functions such as radio resource managementand scheduling, IP header compression, encryption and integrityprotection of data, selection of Access and Mobility Management Function(AMF) at User Equipment (UE) attachment, routing of user plane andcontrol plane data, connection setup and release, scheduling andtransmission of paging messages (originated from the AMF), schedulingand transmission of system broadcast information (originated from theAMF or Operation and Maintenance (O&M)), measurement and measurementreporting configuration, transport level packet marking in the uplink,session management, support of network slicing, Quality of Service (QoS)flow management and mapping to data radio bearers, support of UEs inRRC_INACTIVE state, distribution function for Non-Access Stratum (NAS)messages, RAN sharing, dual connectivity or tight interworking betweenNR and E-UTRA.

In an example, one or more gNBs and/or one or more ng-eNBs may beinterconnected with each other by means of Xn interface. A gNB or anng-eNB may be connected by means of NG interfaces to 5G Core Network(5GC). In an example, 5GC may comprise one or more AMF/User PlanFunction (UPF) functions (e.g. 130A or 130B). A gNB or an ng-eNB may beconnected to a UPF by means of an NG-User plane (NG-U) interface. TheNG-U interface may provide delivery (e.g. non-guaranteed delivery) ofuser plane Protocol Data Units (PDUs) between a RAN node and the UPF. AgNB or an ng-eNB may be connected to an AMF by means of an NG-Controlplane (NG-C) interface. The NG-C interface may provide functions such asNG interface management, UE context management, UE mobility management,transport of NAS messages, paging, PDU session management, configurationtransfer or warning message transmission.

In an example, a UPF may host functions such as anchor point forintra-/inter-Radio Access Technology (RAT) mobility (when applicable),external PDU session point of interconnect to data network, packetrouting and forwarding, packet inspection and user plane part of policyrule enforcement, traffic usage reporting, uplink classifier to supportrouting traffic flows to a data network, branching point to supportmulti-homed PDU session, QoS handling for user plane, e.g. packetfiltering, gating, Uplink (UL)/Downlink (DL) rate enforcement, uplinktraffic verification (e.g. Service Data Flow (SDF) to QoS flow mapping),downlink packet buffering and/or downlink data notification triggering.

In an example, an AMF may host functions such as NAS signalingtermination, NAS signaling security, Access Stratum (AS) securitycontrol, inter Core Network (CN) node signaling for mobility between3^(rd) Generation Partnership Project (3GPP) access networks, idle modeUE reachability (e.g., control and execution of paging retransmission),registration area management, support of intra-system and inter-systemmobility, access authentication, access authorization including check ofroaming rights, mobility management control (subscription and policies),support of network slicing and/or Session Management Function (SMF)selection.

FIG. 2A is an example user plane protocol stack, where Service DataAdaptation Protocol (SDAP) (e.g. 211 and 221), Packet Data ConvergenceProtocol (PDCP) (e.g. 212 and 222), Radio Link Control (RLC) (e.g. 213and 223) and Media Access Control (MAC) (e.g. 214 and 224) sublayers andPhysical (PHY) (e.g. 215 and 225) layer may be terminated in wirelessdevice (e.g. 110) and gNB (e.g. 120) on the network side. In an example,a PHY layer provides transport services to higher layers (e.g. MACand/or RRC). In an example, services and functions of a MAC sublayer maycomprise mapping between logical channels and transport channels,multiplexing/demultiplexing of MAC Service Data Units (SDUs) belongingto one or different logical channels into/from Transport Blocks (TBs)delivered to/from the PHY layer, scheduling information reporting, errorcorrection through Hybrid Automatic Repeat request (HARQ) (e.g. one HARQentity per carrier in case of Carrier Aggregation (CA)), priorityhandling between UEs by means of dynamic scheduling, priority handlingbetween logical channels of one UE by means of logical channelprioritization, and/or padding. A MAC entity may support one or multiplenumerologies and/or transmission timings. In an example, mappingrestrictions in a logical channel prioritization may control whichnumerology and/or transmission timing a logical channel may use. In anexample, an RLC sublayer may supports transparent mode (TM),unacknowledged mode (UM) and acknowledged mode (AM) transmission modes.The RLC configuration may be per logical channel with no dependency onnumerologies and/or Transmission Time Interval (TTI) durations. In anexample, Automatic Repeat Request (ARQ) may operate on any of thenumerologies and/or TTI durations the logical channel is configuredwith. In an example, services and functions of the PDCP layer for theuser plane may comprise sequence numbering, header compression anddecompression, transfer of user data, reordering and duplicatedetection, PDCP PDU routing (e.g. in case of split bearers),retransmission of PDCP SDUs, ciphering, deciphering and integrityprotection, PDCP SDU discard, PDCP re-establishment and data recoveryfor RLC AM, and/or duplication of PDCP PDUs. In an example, services andfunctions of SDAP may comprise mapping between a QoS flow and a dataradio bearer. In an example, services and functions of SDAP may comprisemapping Quality of Service Indicator (QFI) in DL and UL packets. In anexample, a protocol entity of SDAP may be configured for an individualPDU session.

FIG. 2B is an example control plane protocol stack where PDCP (e.g. 233and 242), RLC (e.g. 234 and 243) and MAC (e.g. 235 and 244) sublayersand PHY (e.g. 236 and 245) layer may be terminated in wireless device(e.g. 110) and gNB (e.g. 120) on a network side and perform service andfunctions described above. In an example, RRC (e.g. 232 and 241) may beterminated in a wireless device and a gNB on a network side. In anexample, services and functions of RRC may comprise broadcast of systeminformation related to AS and NAS, paging initiated by 5GC or RAN,establishment, maintenance and release of an RRC connection between theUE and RAN, security functions including key management, establishment,configuration, maintenance and release of Signaling Radio Bearers (SRBs)and Data Radio Bearers (DRBs), mobility functions, QoS managementfunctions, UE measurement reporting and control of the reporting,detection of and recovery from radio link failure, and/or NAS messagetransfer to/from NAS from/to a UE. In an example, NAS control protocol(e.g. 231 and 251) may be terminated in the wireless device and AMF(e.g. 130) on a network side and may perform functions such asauthentication, mobility management between a UE and a AMF for 3GPPaccess and non-3GPP access, and session management between a UE and aSMF for 3GPP access and non-3GPP access.

In an example, a base station may configure a plurality of logicalchannels for a wireless device. A logical channel in the plurality oflogical channels may correspond to a radio bearer and the radio bearermay be associated with a QoS requirement. In an example, a base stationmay configure a logical channel to be mapped to one or moreTTIs/numerologies in a plurality of TTIs/numerologies. The wirelessdevice may receive a Downlink Control Information (DCI) via PhysicalDownlink Control CHannel (PDCCH) indicating an uplink grant. In anexample, the uplink grant may be for a first TTI/numerology and mayindicate uplink resources for transmission of a transport block. Thebase station may configure each logical channel in the plurality oflogical channels with one or more parameters to be used by a logicalchannel prioritization procedure at the MAC layer of the wirelessdevice. The one or more parameters may comprise priority, prioritizedbit rate, etc. A logical channel in the plurality of logical channelsmay correspond to one or more buffers comprising data associated withthe logical channel. The logical channel prioritization procedure mayallocate the uplink resources to one or more first logical channels inthe plurality of logical channels and/or one or more MAC ControlElements (CEs). The one or more first logical channels may be mapped tothe first TTI/numerology. The MAC layer at the wireless device maymultiplex one or more MAC CEs and/or one or more MAC SDUs (e.g., logicalchannel) in a MAC PDU (e.g., transport block). In an example, the MACPDU may comprise a MAC header comprising a plurality of MAC sub-headers.A MAC sub-header in the plurality of MAC sub-headers may correspond to aMAC CE or a MAC SUD (logical channel) in the one or more MAC CEs and/orone or more MAC SDUs. In an example, a MAC CE or a logical channel maybe configured with a Logical Channel IDentifier (LCID). In an example,LCID for a logical channel or a MAC CE may be fixed/semi-staticallyconfigured. In an example, LCID for a logical channel or MAC CE may beconfigured for the wireless device by the base station. The MACsub-header corresponding to a MAC CE or a MAC SDU may comprise LCIDassociated with the MAC CE or the MAC SDU.

In an example, a base station may activate and/or deactivate and/orimpact one or more processes (e.g., set values of one or more parametersof the one or more processes or start and/or stop one or more timers ofthe one or more processes) at the wireless device by employing one ormore MAC commands. The one or more MAC commands may comprise one or moreMAC control elements. In an example, the one or more processes maycomprise activation and/or deactivation of PDCP packet duplication forone or more radio bearers. The base station may transmit a MAC CEcomprising one or more fields, the values of the fields indicatingactivation and/or deactivation of PDCP duplication for the one or moreradio bearers. In an example, the one or more processes may compriseChannel State Information (CSI) transmission of on one or more cells.The base station may transmit one or more MAC CEs indicating activationand/or deactivation of the CSI transmission on the one or more cells. Inan example, the one or more processes may comprise activation ordeactivation of one or more secondary cells. In an example, the basestation may transmit a MA CE indicating activation or deactivation ofone or more secondary cells. In an example, the base station maytransmit one or more MAC CEs indicating starting and/or stopping one ormore Discontinuous Reception (DRX) timers at the wireless device. In anexample, the base station may transmit one or more MAC CEs indicatingone or more timing advance values for one or more Timing Advance Groups(TAGs).

FIG. 3 is a block diagram of base stations (base station 1, 120A, andbase station 2, 120B) and a wireless device 110. A wireless device maybe called an UE. A base station may be called a NB, eNB, gNB, and/orng-eNB. In an example, a wireless device and/or a base station may actas a relay node. The base station 1, 120A, may comprise at least onecommunication interface 320A (e.g. a wireless modem, an antenna, a wiredmodem, and/or the like), at least one processor 321A, and at least oneset of program code instructions 323A stored in non-transitory memory322A and executable by the at least one processor 321A. The base station2, 120B, may comprise at least one communication interface 320B, atleast one processor 321B, and at least one set of program codeinstructions 323B stored in non-transitory memory 322B and executable bythe at least one processor 321B.

A base station may comprise many sectors for example: 1, 2, 3, 4, or 6sectors. A base station may comprise many cells, for example, rangingfrom 1 to 50 cells or more. A cell may be categorized, for example, as aprimary cell or secondary cell. At Radio Resource Control (RRC)connection establishment/re-establishment/handover, one serving cell mayprovide the NAS (non-access stratum) mobility information (e.g. TrackingArea Identifier (TAI)). At RRC connection re-establishment/handover, oneserving cell may provide the security input. This cell may be referredto as the Primary Cell (PCell). In the downlink, a carrier correspondingto the PCell may be a DL Primary Component Carrier (PCC), while in theuplink, a carrier may be an UL PCC. Depending on wireless devicecapabilities, Secondary Cells (SCells) may be configured to formtogether with a PCell a set of serving cells. In a downlink, a carriercorresponding to an SCell may be a downlink secondary component carrier(DL SCC), while in an uplink, a carrier may be an uplink secondarycomponent carrier (UL SCC). An SCell may or may not have an uplinkcarrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned a physical cell ID and a cell index. A carrier (downlinkor uplink) may belong to one cell. The cell ID or cell index may alsoidentify the downlink carrier or uplink carrier of the cell (dependingon the context it is used). In the disclosure, a cell ID may be equallyreferred to a carrier ID, and a cell index may be referred to a carrierindex. In an implementation, a physical cell ID or a cell index may beassigned to a cell. A cell ID may be determined using a synchronizationsignal transmitted on a downlink carrier. A cell index may be determinedusing RRC messages. For example, when the disclosure refers to a firstphysical cell ID for a first downlink carrier, the disclosure may meanthe first physical cell ID is for a cell comprising the first downlinkcarrier. The same concept may apply to, for example, carrier activation.When the disclosure indicates that a first carrier is activated, thespecification may equally mean that a cell comprising the first carrieris activated.

A base station may transmit to a wireless device one or more messages(e.g. RRC messages) comprising a plurality of configuration parametersfor one or more cells. One or more cells may comprise at least oneprimary cell and at least one secondary cell. In an example, an RRCmessage may be broadcasted or unicasted to the wireless device. In anexample, configuration parameters may comprise common parameters anddedicated parameters.

Services and/or functions of an RRC sublayer may comprise at least oneof: broadcast of system information related to AS and NAS; paginginitiated by 5GC and/or NG-RAN; establishment, maintenance, and/orrelease of an RRC connection between a wireless device and NG-RAN, whichmay comprise at least one of addition, modification and release ofcarrier aggregation; or addition, modification, and/or release of dualconnectivity in NR or between E-UTRA and NR. Services and/or functionsof an RRC sublayer may further comprise at least one of securityfunctions comprising key management; establishment, configuration,maintenance, and/or release of Signaling Radio Bearers (SRBs) and/orData Radio Bearers (DRBs); mobility functions which may comprise atleast one of a handover (e.g. intra NR mobility or inter-RAT mobility)and a context transfer; or a wireless device cell selection andreselection and control of cell selection and reselection. Servicesand/or functions of an RRC sublayer may further comprise at least one ofQoS management functions; a wireless device measurementconfiguration/reporting; detection of and/or recovery from radio linkfailure; or NAS message transfer to/from a core network entity (e.g.AMF, Mobility Management Entity (MME)) from/to the wireless device.

An RRC sublayer may support an RRC_Idle state, an RRC_Inactive stateand/or an RRC_Connected state for a wireless device. In an RRC_Idlestate, a wireless device may perform at least one of: Public Land MobileNetwork (PLMN) selection; receiving broadcasted system information; cellselection/re-selection; monitoring/receiving a paging for mobileterminated data initiated by 5GC; paging for mobile terminated data areamanaged by 5GC; or DRX for CN paging configured via NAS. In anRRC_Inactive state, a wireless device may perform at least one of:receiving broadcasted system information; cell selection/re-selection;monitoring/receiving a RAN/CN paging initiated by NG-RAN/5GC; RAN-basednotification area (RNA) managed by NG-RAN; or DRX for RAN/CN pagingconfigured by NG-RAN/NAS. In an RRC_Idle state of a wireless device, abase station (e.g. NG-RAN) may keep a 5GC-NG-RAN connection (bothC/U-planes) for the wireless device; and/or store a UE AS context forthe wireless device. In an RRC_Connected state of a wireless device, abase station (e.g. NG-RAN) may perform at least one of: establishment of5GC-NG-RAN connection (both C/U-planes) for the wireless device; storinga UE AS context for the wireless device; transmit/receive of unicastdata to/from the wireless device; or network-controlled mobility basedon measurement results received from the wireless device. In anRRC_Connected state of a wireless device, an NG-RAN may know a cell thatthe wireless device belongs to.

System information (SI) may be divided into minimum SI and other SI. Theminimum SI may be periodically broadcast. The minimum SI may comprisebasic information required for initial access and information foracquiring any other SI broadcast periodically or provisioned on-demand,i.e. scheduling information. The other SI may either be broadcast, or beprovisioned in a dedicated manner, either triggered by a network or uponrequest from a wireless device. A minimum SI may be transmitted via twodifferent downlink channels using different messages (e.g.MasterInformationBlock and SystemInformationBlockType1). An other SI maybe transmitted via SystemInformationBlockType2. For a wireless device inan RRC_Connected state, dedicated RRC signaling may be employed for therequest and delivery of the other SI. For the wireless device in theRRC_Idle state and/or the RRC_Inactive state, the request may trigger arandom-access procedure.

A wireless device may report its radio access capability informationwhich may be static. A base station may request what capabilities for awireless device to report based on band information. When allowed by anetwork, a temporary capability restriction request may be sent by thewireless device to signal the limited availability of some capabilities(e.g. due to hardware sharing, interference or overheating) to the basestation. The base station may confirm or reject the request. Thetemporary capability restriction may be transparent to 5GC (e.g., staticcapabilities may be stored in 5GC).

When CA is configured, a wireless device may have an RRC connection witha network. At RRC connection establishment/re-establishment/handoverprocedure, one serving cell may provide NAS mobility information, and atRRC connection re-establishment/handover, one serving cell may provide asecurity input. This cell may be referred to as the PCell. Depending onthe capabilities of the wireless device, SCells may be configured toform together with the PCell a set of serving cells. The configured setof serving cells for the wireless device may comprise one PCell and oneor more SCells.

The reconfiguration, addition and removal of SCells may be performed byRRC. At intra-NR handover, RRC may also add, remove, or reconfigureSCells for usage with the target PCell. When adding a new SCell,dedicated RRC signaling may be employed to send all required systeminformation of the SCell i.e. while in connected mode, wireless devicesmay not need to acquire broadcasted system information directly from theSCells.

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells and cell groups). As part of the RRCconnection reconfiguration procedure, NAS dedicated information may betransferred from the network to the wireless device. TheRRCConnectionReconfiguration message may be a command to modify an RRCconnection. It may convey information for measurement configuration,mobility control, radio resource configuration (e.g. RBs, MAC mainconfiguration and physical channel configuration) comprising anyassociated dedicated NAS information and security configuration. If thereceived RRC Connection Reconfiguration message includes thesCellToReleaseList, the wireless device may perform an SCell release. Ifthe received RRC Connection Reconfiguration message includes thesCellToAddModList, the wireless device may perform SCell additions ormodification.

An RRC connection establishment (or reestablishment, resume) proceduremay be to establish (or reestablish, resume) an RRC connection. an RRCconnection establishment procedure may comprise SRB1 establishment. TheRRC connection establishment procedure may be used to transfer theinitial NAS dedicated information/message from a wireless device toE-UTRAN. The RRCConnectionReestablishment message may be used toreestablish SRB1.

A measurement report procedure may be to transfer measurement resultsfrom a wireless device to NG-RAN. The wireless device may initiate ameasurement report procedure after successful security activation. Ameasurement report message may be employed to transmit measurementresults.

The wireless device 110 may comprise at least one communicationinterface 310 (e.g. a wireless modem, an antenna, and/or the like), atleast one processor 314, and at least one set of program codeinstructions 316 stored in non-transitory memory 315 and executable bythe at least one processor 314. The wireless device 110 may furthercomprise at least one of at least one speaker/microphone 311, at leastone keypad 312, at least one display/touchpad 313, at least one powersource 317, at least one global positioning system (GPS) chipset 318,and other peripherals 319.

The processor 314 of the wireless device 110, the processor 321A of thebase station 1 120A, and/or the processor 321B of the base station 2120B may comprise at least one of a general-purpose processor, a digitalsignal processor (DSP), a controller, a microcontroller, an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) and/or other programmable logic device, discrete gate and/ortransistor logic, discrete hardware components, and the like. Theprocessor 314 of the wireless device 110, the processor 321A in basestation 1 120A, and/or the processor 321B in base station 2 120B mayperform at least one of signal coding/processing, data processing, powercontrol, input/output processing, and/or any other functionality thatmay enable the wireless device 110, the base station 1 120A and/or thebase station 2 120B to operate in a wireless environment.

The processor 314 of the wireless device 110 may be connected to thespeaker/microphone 311, the keypad 312, and/or the display/touchpad 313.The processor 314 may receive user input data from and/or provide useroutput data to the speaker/microphone 311, the keypad 312, and/or thedisplay/touchpad 313. The processor 314 in the wireless device 110 mayreceive power from the power source 317 and/or may be configured todistribute the power to the other components in the wireless device 110.The power source 317 may comprise at least one of one or more dry cellbatteries, solar cells, fuel cells, and the like. The processor 314 maybe connected to the GPS chipset 318. The GPS chipset 318 may beconfigured to provide geographic location information of the wirelessdevice 110.

The processor 314 of the wireless device 110 may further be connected toother peripherals 319, which may comprise one or more software and/orhardware modules that provide additional features and/orfunctionalities. For example, the peripherals 319 may comprise at leastone of an accelerometer, a satellite transceiver, a digital camera, auniversal serial bus (USB) port, a hands-free headset, a frequencymodulated (FM) radio unit, a media player, an Internet browser, and thelike.

The communication interface 320A of the base station 1, 120A, and/or thecommunication interface 320B of the base station 2, 120B, may beconfigured to communicate with the communication interface 310 of thewireless device 110 via a wireless link 330A and/or a wireless link 330Brespectively. In an example, the communication interface 320A of thebase station 1, 120A, may communicate with the communication interface320B of the base station 2 and other RAN and core network nodes.

The wireless link 330A and/or the wireless link 330B may comprise atleast one of a bi-directional link and/or a directional link. Thecommunication interface 310 of the wireless device 110 may be configuredto communicate with the communication interface 320A of the base station1 120A and/or with the communication interface 320B of the base station2 120B. The base station 1 120A and the wireless device 110 and/or thebase station 2 120B and the wireless device 110 may be configured tosend and receive transport blocks via the wireless link 330A and/or viathe wireless link 330B, respectively. The wireless link 330A and/or thewireless link 330B may employ at least one frequency carrier. Accordingto some of various aspects of embodiments, transceiver(s) may beemployed. A transceiver may be a device that comprises both atransmitter and a receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in thecommunication interface 310, 320A, 320B and the wireless link 330A, 330Bare illustrated in FIG. 4A, FIG. 4B, FIG. 4C, FIG. 4D, FIG. 6, FIG. 7A,FIG. 7B, FIG. 8, and associated text.

In an example, other nodes in a wireless network (e.g. AMF, UPF, SMF,etc.) may comprise one or more communication interfaces, one or moreprocessors, and memory storing instructions.

A node (e.g. wireless device, base station, AMF, SMF, UPF, servers,switches, antennas, and/or the like) may comprise one or moreprocessors, and memory storing instructions that when executed by theone or more processors causes the node to perform certain processesand/or functions. Example embodiments may enable operation ofsingle-carrier and/or multi-carrier communications. Other exampleembodiments may comprise a non-transitory tangible computer readablemedia comprising instructions executable by one or more processors tocause operation of single-carrier and/or multi-carrier communications.Yet other example embodiments may comprise an article of manufacturethat comprises a non-transitory tangible computer readablemachine-accessible medium having instructions encoded thereon forenabling programmable hardware to cause a node to enable operation ofsingle-carrier and/or multi-carrier communications. The node may includeprocessors, memory, interfaces, and/or the like.

An interface may comprise at least one of a hardware interface, afirmware interface, a software interface, and/or a combination thereof.The hardware interface may comprise connectors, wires, electronicdevices such as drivers, amplifiers, and/or the like. The softwareinterface may comprise code stored in a memory device to implementprotocol(s), protocol layers, communication drivers, device drivers,combinations thereof, and/or the like. The firmware interface maycomprise a combination of embedded hardware and code stored in and/or incommunication with a memory device to implement connections, electronicdevice operations, protocol(s), protocol layers, communication drivers,device drivers, hardware operations, combinations thereof, and/or thelike.

FIG. 4A, FIG. 4B, FIG. 4C and FIG. 4D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure. FIG. 4A shows an example uplink transmitter forat least one physical channel. A baseband signal representing a physicaluplink shared channel may perform one or more functions. The one or morefunctions may comprise at least one of: scrambling; modulation ofscrambled bits to generate complex-valued symbols; mapping of thecomplex-valued modulation symbols onto one or several transmissionlayers; transform precoding to generate complex-valued symbols;precoding of the complex-valued symbols; mapping of precodedcomplex-valued symbols to resource elements; generation ofcomplex-valued time-domain Single Carrier-Frequency Division MultipleAccess (SC-FDMA) or CP-OFDM signal for an antenna port; and/or the like.In an example, when transform precoding is enabled, a SC-FDMA signal foruplink transmission may be generated. In an example, when transformprecoding is not enabled, an CP-OFDM signal for uplink transmission maybe generated by FIG. 4A. These functions are illustrated as examples andit is anticipated that other mechanisms may be implemented in variousembodiments.

An example structure for modulation and up-conversion to the carrierfrequency of the complex-valued SC-FDMA or CP-OFDM baseband signal foran antenna port and/or the complex-valued Physical Random Access CHannel(PRACH) baseband signal is shown in FIG. 4B. Filtering may be employedprior to transmission.

An example structure for downlink transmissions is shown in FIG. 4C. Thebaseband signal representing a downlink physical channel may perform oneor more functions. The one or more functions may comprise: scrambling ofcoded bits in a codeword to be transmitted on a physical channel;modulation of scrambled bits to generate complex-valued modulationsymbols; mapping of the complex-valued modulation symbols onto one orseveral transmission layers; precoding of the complex-valued modulationsymbols on a layer for transmission on the antenna ports; mapping ofcomplex-valued modulation symbols for an antenna port to resourceelements; generation of complex-valued time-domain OFDM signal for anantenna port; and/or the like. These functions are illustrated asexamples and it is anticipated that other mechanisms may be implementedin various embodiments.

In an example, a gNB may transmit a first symbol and a second symbol onan antenna port, to a wireless device. The wireless device may infer thechannel (e.g., fading gain, multipath delay, etc.) for conveying thesecond symbol on the antenna port, from the channel for conveying thefirst symbol on the antenna port. In an example, a first antenna portand a second antenna port may be quasi co-located if one or morelarge-scale properties of the channel over which a first symbol on thefirst antenna port is conveyed may be inferred from the channel overwhich a second symbol on a second antenna port is conveyed. The one ormore large-scale properties may comprise at least one of: delay spread;doppler spread; doppler shift; average gain; average delay; and/orspatial Receiving (Rx) parameters.

An example modulation and up-conversion to the carrier frequency of thecomplex-valued OFDM baseband signal for an antenna port is shown in FIG.4D. Filtering may be employed prior to transmission.

FIG. 5A is a diagram of an example uplink channel mapping and exampleuplink physical signals. FIG. 5B is a diagram of an example downlinkchannel mapping and a downlink physical signals. In an example, aphysical layer may provide one or more information transfer services toa MAC and/or one or more higher layers. For example, the physical layermay provide the one or more information transfer services to the MAC viaone or more transport channels. An information transfer service mayindicate how and with what characteristics data are transferred over theradio interface.

In an example embodiment, a radio network may comprise one or moredownlink and/or uplink transport channels. For example, a diagram inFIG. 5A shows example uplink transport channels comprising Uplink-SharedCHannel (UL-SCH) 501 and Random Access CHannel (RACH) 502. A diagram inFIG. 5B shows example downlink transport channels comprisingDownlink-Shared CHannel (DL-SCH) 511, Paging CHannel (PCH) 512, andBroadcast CHannel (BCH) 513. A transport channel may be mapped to one ormore corresponding physical channels. For example, UL-SCH 501 may bemapped to Physical Uplink Shared CHannel (PUSCH) 503. RACH 502 may bemapped to PRACH 505. DL-SCH 511 and PCH 512 may be mapped to PhysicalDownlink Shared CHannel (PDSCH) 514. BCH 513 may be mapped to PhysicalBroadcast CHannel (PBCH) 516.

There may be one or more physical channels without a correspondingtransport channel. The one or more physical channels may be employed forUplink Control Information (UCI) 509 and/or Downlink Control Information(DCI) 517. For example, Physical Uplink Control CHannel (PUCCH) 504 maycarry UCI 509 from a UE to a base station. For example, PhysicalDownlink Control CHannel (PDCCH) 515 may carry DCI 517 from a basestation to a UE. NR may support UCI 509 multiplexing in PUSCH 503 whenUCI 509 and PUSCH 503 transmissions may coincide in a slot at least inpart. The UCI 509 may comprise at least one of CSI, Acknowledgement(ACK)/Negative Acknowledgement (NACK), and/or scheduling request. TheDCI 517 on PDCCH 515 may indicate at least one of following: one or moredownlink assignments and/or one or more uplink scheduling grants

In uplink, a UE may transmit one or more Reference Signals (RSs) to abase station. For example, the one or more RSs may be at least one ofDemodulation-RS (DM-RS) 506, Phase Tracking-RS (PT-RS) 507, and/orSounding RS (SRS) 508. In downlink, a base station may transmit (e.g.,unicast, multicast, and/or broadcast) one or more RSs to a UE. Forexample, the one or more RSs may be at least one of PrimarySynchronization Signal (PSS)/Secondary Synchronization Signal (SSS) 521,CSI-RS 522, DM-RS 523, and/or PT-RS 524.

In an example, a UE may transmit one or more uplink DM-RSs 506 to a basestation for channel estimation, for example, for coherent demodulationof one or more uplink physical channels (e.g., PUSCH 503 and/or PUCCH504). For example, a UE may transmit a base station at least one uplinkDM-RS 506 with PUSCH 503 and/or PUCCH 504, wherein the at least oneuplink DM-RS 506 may be spanning a same frequency range as acorresponding physical channel. In an example, a base station mayconfigure a UE with one or more uplink DM-RS configurations. At leastone DM-RS configuration may support a front-loaded DM-RS pattern. Afront-loaded DM-RS may be mapped over one or more OFDM symbols (e.g., 1or 2 adjacent OFDM symbols). One or more additional uplink DM-RS may beconfigured to transmit at one or more symbols of a PUSCH and/or PUCCH. Abase station may semi-statically configure a UE with a maximum number offront-loaded DM-RS symbols for PUSCH and/or PUCCH. For example, a UE mayschedule a single-symbol DM-RS and/or double symbol DM-RS based on amaximum number of front-loaded DM-RS symbols, wherein a base station mayconfigure the UE with one or more additional uplink DM-RS for PUSCHand/or PUCCH. A new radio network may support, e.g., at least forCP-OFDM, a common DM-RS structure for DL and UL, wherein a DM-RSlocation, DM-RS pattern, and/or scrambling sequence may be same ordifferent.

In an example, whether uplink PT-RS 507 is present or not may depend ona RRC configuration. For example, a presence of uplink PT-RS may beUE-specifically configured. For example, a presence and/or a pattern ofuplink PT-RS 507 in a scheduled resource may be UE-specificallyconfigured by a combination of RRC signaling and/or association with oneor more parameters employed for other purposes (e.g., Modulation andCoding Scheme (MCS)) which may be indicated by DCI. When configured, adynamic presence of uplink PT-RS 507 may be associated with one or moreDCI parameters comprising at least MCS. A radio network may supportplurality of uplink PT-RS densities defined in time/frequency domain.When present, a frequency domain density may be associated with at leastone configuration of a scheduled bandwidth. A UE may assume a sameprecoding for a DMRS port and a PT-RS port. A number of PT-RS ports maybe fewer than a number of DM-RS ports in a scheduled resource. Forexample, uplink PT-RS 507 may be confined in the scheduledtime/frequency duration for a UE.

In an example, a UE may transmit SRS 508 to a base station for channelstate estimation to support uplink channel dependent scheduling and/orlink adaptation. For example, SRS 508 transmitted by a UE may allow fora base station to estimate an uplink channel state at one or moredifferent frequencies. A base station scheduler may employ an uplinkchannel state to assign one or more resource blocks of good quality foran uplink PUSCH transmission from a UE. A base station maysemi-statically configure a UE with one or more SRS resource sets. Foran SRS resource set, a base station may configure a UE with one or moreSRS resources. An SRS resource set applicability may be configured by ahigher layer (e.g., RRC) parameter. For example, when a higher layerparameter indicates beam management, a SRS resource in each of one ormore SRS resource sets may be transmitted at a time instant. A UE maytransmit one or more SRS resources in different SRS resource setssimultaneously. A new radio network may support aperiodic, periodicand/or semi-persistent SRS transmissions. A UE may transmit SRSresources based on one or more trigger types, wherein the one or moretrigger types may comprise higher layer signaling (e.g., RRC) and/or oneor more DCI formats (e.g., at least one DCI format may be employed for aUE to select at least one of one or more configured SRS resource sets.An SRS trigger type 0 may refer to an SRS triggered based on a higherlayer signaling. An SRS trigger type 1 may refer to an SRS triggeredbased on one or more DCI formats. In an example, when PUSCH 503 and SRS508 are transmitted in a same slot, a UE may be configured to transmitSRS 508 after a transmission of PUSCH 503 and corresponding uplink DM-RS506.

In an example, a base station may semi-statically configure a UE withone or more SRS configuration parameters indicating at least one offollowing: a SRS resource configuration identifier, a number of SRSports, time domain behavior of SRS resource configuration (e.g., anindication of periodic, semi-persistent, or aperiodic SRS), slot(mini-slot, and/or subframe) level periodicity and/or offset for aperiodic and/or aperiodic SRS resource, a number of OFDM symbols in aSRS resource, starting OFDM symbol of a SRS resource, a SRS bandwidth, afrequency hopping bandwidth, a cyclic shift, and/or a SRS sequence ID.

In an example, in a time domain, an SS/PBCH block may comprise one ormore OFDM symbols (e.g., 4 OFDM symbols numbered in increasing orderfrom 0 to 3) within the SS/PBCH block. An SS/PBCH block may comprisePSS/SSS 521 and PBCH 516. In an example, in the frequency domain, anSS/PBCH block may comprise one or more contiguous subcarriers (e.g., 240contiguous subcarriers with the subcarriers numbered in increasing orderfrom 0 to 239) within the SS/PBCH block. For example, a PSS/SSS 521 mayoccupy 1 OFDM symbol and 127 subcarriers. For example, PBCH 516 may spanacross 3 OFDM symbols and 240 subcarriers. A UE may assume that one ormore SS/PBCH blocks transmitted with a same block index may be quasico-located, e.g., with respect to Doppler spread, Doppler shift, averagegain, average delay, and spatial Rx parameters. A UE may not assumequasi co-location for other SS/PBCH block transmissions. A periodicityof an SS/PBCH block may be configured by a radio network (e.g., by anRRC signaling) and one or more time locations where the SS/PBCH blockmay be sent may be determined by sub-carrier spacing. In an example, aUE may assume a band-specific sub-carrier spacing for an SS/PBCH blockunless a radio network has configured a UE to assume a differentsub-carrier spacing.

In an example, downlink CSI-RS 522 may be employed for a UE to acquirechannel state information. A radio network may support periodic,aperiodic, and/or semi-persistent transmission of downlink CSI-RS 522.For example, a base station may semi-statically configure and/orreconfigure a UE with periodic transmission of downlink CSI-RS 522. Aconfigured CSI-RS resources may be activated ad/or deactivated. Forsemi-persistent transmission, an activation and/or deactivation ofCSI-RS resource may be triggered dynamically. In an example, CSI-RSconfiguration may comprise one or more parameters indicating at least anumber of antenna ports. For example, a base station may configure a UEwith 32 ports. A base station may semi-statically configure a UE withone or more CSI-RS resource sets. One or more CSI-RS resources may beallocated from one or more CSI-RS resource sets to one or more UEs. Forexample, a base station may semi-statically configure one or moreparameters indicating CSI RS resource mapping, for example, time-domainlocation of one or more CSI-RS resources, a bandwidth of a CSI-RSresource, and/or a periodicity. In an example, a UE may be configured toemploy a same OFDM symbols for downlink CSI-RS 522 and control resourceset (coreset) when the downlink CSI-RS 522 and coreset are spatiallyquasi co-located and resource elements associated with the downlinkCSI-RS 522 are the outside of PRBs configured for coreset. In anexample, a UE may be configured to employ a same OFDM symbols fordownlink CSI-RS 522 and SSB/PBCH when the downlink CSI-RS 522 andSSB/PBCH are spatially quasi co-located and resource elements associatedwith the downlink CSI-RS 522 are the outside of PRBs configured forSSB/PBCH.

In an example, a UE may transmit one or more downlink DM-RSs 523 to abase station for channel estimation, for example, for coherentdemodulation of one or more downlink physical channels (e.g., PDSCH514). For example, a radio network may support one or more variableand/or configurable DM-RS patterns for data demodulation. At least onedownlink DM-RS configuration may support a front-loaded DM-RS pattern. Afront-loaded DM-RS may be mapped over one or more OFDM symbols (e.g., 1or 2 adjacent OFDM symbols). A base station may semi-staticallyconfigure a UE with a maximum number of front-loaded DM-RS symbols forPDSCH 514. For example, a DM-RS configuration may support one or moreDM-RS ports. For example, for single user-MIMO, a DM-RS configurationmay support at least 8 orthogonal downlink DM-RS ports. For example, formultiuser-MIMO, a DM-RS configuration may support 12 orthogonal downlinkDM-RS ports. A radio network may support, e.g., at least for CP-OFDM, acommon DM-RS structure for DL and UL, wherein a DM-RS location, DM-RSpattern, and/or scrambling sequence may be same or different.

In an example, whether downlink PT-RS 524 is present or not may dependon a RRC configuration. For example, a presence of downlink PT-RS 524may be UE-specifically configured. For example, a presence and/or apattern of downlink PT-RS 524 in a scheduled resource may beUE-specifically configured by a combination of RRC signaling and/orassociation with one or more parameters employed for other purposes(e.g., MCS) which may be indicated by DCI. When configured, a dynamicpresence of downlink PT-RS 524 may be associated with one or more DCIparameters comprising at least MCS. A radio network may supportplurality of PT-RS densities defined in time/frequency domain. Whenpresent, a frequency domain density may be associated with at least oneconfiguration of a scheduled bandwidth. A UE may assume a same precodingfor a DMRS port and a PT-RS port. A number of PT-RS ports may be fewerthan a number of DM-RS ports in a scheduled resource. For example,downlink PT-RS 524 may be confined in the scheduled time/frequencyduration for a UE.

FIG. 6 is a diagram depicting an example frame structure for a carrieras per an aspect of an embodiment of the present disclosure. Amulticarrier OFDM communication system may include one or more carriers,for example, ranging from 1 to 32 carriers, in case of carrieraggregation, or ranging from 1 to 64 carriers, in case of dualconnectivity. Different radio frame structures may be supported (e.g.,for FDD and for TDD duplex mechanisms). FIG. 6 shows an example framestructure. Downlink and uplink transmissions may be organized into radioframes 601. In this example, radio frame duration is 10 ms. In thisexample, a 10 ms radio frame 601 may be divided into ten equally sizedsubframes 602 with 1 ms duration. Subframe(s) may comprise one or moreslots (e.g. slots 603 and 605) depending on subcarrier spacing and/or CPlength. For example, a subframe with 15 kHz, 30 kHz, 60 kHz, 120 kHz,240 kHz and 480 kHz subcarrier spacing may comprise one, two, four,eight, sixteen and thirty-two slots, respectively. In FIG. 6, a subframemay be divided into two equally sized slots 603 with 0.5 ms duration.For example, 10 subframes may be available for downlink transmission and10 subframes may be available for uplink transmissions in a 10 msinterval. Uplink and downlink transmissions may be separated in thefrequency domain. Slot(s) may include a plurality of OFDM symbols 604.The number of OFDM symbols 604 in a slot 605 may depend on the cyclicprefix length. For example, a slot may be 14 OFDM symbols for the samesubcarrier spacing of up to 480 kHz with normal CP. A slot may be 12OFDM symbols for the same subcarrier spacing of 60 kHz with extended CP.A slot may contain downlink, uplink, or a downlink part and an uplinkpart and/or alike.

FIG. 7A is a diagram depicting example sets of OFDM subcarriers as peran aspect of an embodiment of the present disclosure. In the example, agNB may communicate with a wireless device with a carrier with anexample channel bandwidth 700. Arrow(s) in the diagram may depict asubcarrier in a multicarrier OFDM system. The OFDM system may usetechnology such as OFDM technology, SC-FDMA technology, and/or the like.In an example, an arrow 701 shows a subcarrier transmitting informationsymbols. In an example, a subcarrier spacing 702, between two contiguoussubcarriers in a carrier, may be any one of 15 KHz, 30 KHz, 60 KHz, 120KHz, 240 KHz etc. In an example, different subcarrier spacing maycorrespond to different transmission numerologies. In an example, atransmission numerology may comprise at least: a numerology index; avalue of subcarrier spacing; a type of cyclic prefix (CP). In anexample, a gNB may transmit to/receive from a UE on a number ofsubcarriers 703 in a carrier. In an example, a bandwidth occupied by anumber of subcarriers 703 (transmission bandwidth) may be smaller thanthe channel bandwidth 700 of a carrier, due to guard band 704 and 705.In an example, a guard band 704 and 705 may be used to reduceinterference to and from one or more neighbor carriers. A number ofsubcarriers (transmission bandwidth) in a carrier may depend on thechannel bandwidth of the carrier and the subcarrier spacing. Forexample, a transmission bandwidth, for a carrier with 20 MHz channelbandwidth and 15 KHz subcarrier spacing, may be in number of 1024subcarriers.

In an example, a gNB and a wireless device may communicate with multipleCCs when configured with CA. In an example, different component carriersmay have different bandwidth and/or subcarrier spacing, if CA issupported. In an example, a gNB may transmit a first type of service toa UE on a first component carrier. The gNB may transmit a second type ofservice to the UE on a second component carrier. Different type ofservices may have different service requirement (e.g., data rate,latency, reliability), which may be suitable for transmission viadifferent component carrier having different subcarrier spacing and/orbandwidth. FIG. 7B shows an example embodiment. A first componentcarrier may comprise a first number of subcarriers 706 with a firstsubcarrier spacing 709. A second component carrier may comprise a secondnumber of subcarriers 707 with a second subcarrier spacing 710. A thirdcomponent carrier may comprise a third number of subcarriers 708 with athird subcarrier spacing 711. Carriers in a multicarrier OFDMcommunication system may be contiguous carriers, non-contiguouscarriers, or a combination of both contiguous and non-contiguouscarriers.

FIG. 8 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present disclosure. In an example, a carrier mayhave a transmission bandwidth 801. In an example, a resource grid may bein a structure of frequency domain 802 and time domain 803. In anexample, a resource grid may comprise a first number of OFDM symbols ina subframe and a second number of resource blocks, starting from acommon resource block indicated by higher-layer signaling (e.g. RRCsignaling), for a transmission numerology and a carrier. In an example,in a resource grid, a resource unit identified by a subcarrier index anda symbol index may be a resource element 805. In an example, a subframemay comprise a first number of OFDM symbols 807 depending on anumerology associated with a carrier. For example, when a subcarrierspacing of a numerology of a carrier is 15 KHz, a subframe may have 14OFDM symbols for a carrier. When a subcarrier spacing of a numerology is30 KHz, a subframe may have 28 OFDM symbols. When a subcarrier spacingof a numerology is 60 Khz, a subframe may have 56 OFDM symbols, etc. Inan example, a second number of resource blocks comprised in a resourcegrid of a carrier may depend on a bandwidth and a numerology of thecarrier.

As shown in FIG. 8, a resource block 806 may comprise 12 subcarriers. Inan example, multiple resource blocks may be grouped into a ResourceBlock Group (RBG) 804. In an example, a size of a RBG may depend on atleast one of: a RRC message indicating a RBG size configuration; a sizeof a carrier bandwidth; or a size of a bandwidth part of a carrier. Inan example, a carrier may comprise multiple bandwidth parts. A firstbandwidth part of a carrier may have different frequency location and/orbandwidth from a second bandwidth part of the carrier.

In an example, a gNB may transmit a downlink control informationcomprising a downlink or uplink resource block assignment to a wirelessdevice. A base station may transmit to or receive from, a wirelessdevice, data packets (e.g. transport blocks) scheduled and transmittedvia one or more resource blocks and one or more slots according toparameters in a downlink control information and/or RRC message(s). Inan example, a starting symbol relative to a first slot of the one ormore slots may be indicated to the wireless device. In an example, a gNBmay transmit to or receive from, a wireless device, data packetsscheduled on one or more RBGs and one or more slots.

In an example, a gNB may transmit a downlink control informationcomprising a downlink assignment to a wireless device via one or morePDCCHs. The downlink assignment may comprise parameters indicating atleast modulation and coding format; resource allocation; and/or HARQinformation related to DL-SCH. In an example, a resource allocation maycomprise parameters of resource block allocation; and/or slotallocation. In an example, a gNB may dynamically allocate resources to awireless device via a Cell-Radio Network Temporary Identifier (C-RNTI)on one or more PDCCHs. The wireless device may monitor the one or morePDCCHs in order to find possible allocation when its downlink receptionis enabled. The wireless device may receive one or more downlink datapackage on one or more PDSCH scheduled by the one or more PDCCHs, whensuccessfully detecting the one or more PDCCHs.

In an example, a gNB may allocate Configured Scheduling (CS) resourcesfor down link transmission to a wireless device. The gNB may transmitone or more RRC messages indicating a periodicity of the CS grant. ThegNB may transmit a DCI via a PDCCH addressed to a ConfiguredScheduling-RNTI (CS-RNTI) activating the CS resources. The DCI maycomprise parameters indicating that the downlink grant is a CS grant.The CS grant may be implicitly reused according to the periodicitydefined by the one or more RRC messages, until deactivated.

In an example, a gNB may transmit a downlink control informationcomprising an uplink grant to a wireless device via one or more PDCCHs.The uplink grant may comprise parameters indicating at least modulationand coding format; resource allocation; and/or HARQ information relatedto UL-SCH. In an example, a resource allocation may comprise parametersof resource block allocation; and/or slot allocation. In an example, agNB may dynamically allocate resources to a wireless device via a C-RNTIon one or more PDCCHs. The wireless device may monitor the one or morePDCCHs in order to find possible resource allocation. The wirelessdevice may transmit one or more uplink data package via one or morePUSCH scheduled by the one or more PDCCHs, when successfully detectingthe one or more PDCCHs.

In an example, a gNB may allocate CS resources for uplink datatransmission to a wireless device. The gNB may transmit one or more RRCmessages indicating a periodicity of the CS grant. The gNB may transmita DCI via a PDCCH addressed to a CS-RNTI activating the CS resources.The DCI may comprise parameters indicating that the uplink grant is a CSgrant. The CS grant may be implicitly reused according to theperiodicity defined by the one or more RRC message, until deactivated.

In an example, a base station may transmit DCI/control signaling viaPDCCH. The DCI may take a format in a plurality of formats. A DCI maycomprise downlink and/or uplink scheduling information (e.g., resourceallocation information, HARQ related parameters, MCS), request for CSI(e.g., aperiodic CQI reports), request for SRS, uplink power controlcommands for one or more cells, one or more timing information (e.g., TBtransmission/reception timing, HARQ feedback timing, etc.), etc. In anexample, a DCI may indicate an uplink grant comprising transmissionparameters for one or more transport blocks. In an example, a DCI mayindicate downlink assignment indicating parameters for receiving one ormore transport blocks. In an example, a DCI may be used by base stationto initiate a contention-free random access at the wireless device. Inan example, the base station may transmit a DCI comprising slot formatindicator (SFI) notifying a slot format. In an example, the base stationmay transmit a DCI comprising pre-emption indication notifying thePRB(s) and/or OFDM symbol(s) where a UE may assume no transmission isintended for the UE. In an example, the base station may transmit a DCIfor group power control of PUCCH or PUSCH or SRS. In an example, a DCImay correspond to an RNTI. In an example, the wireless device may obtainan RNTI in response to completing the initial access (e.g., C-RNTI). Inan example, the base station may configure an RNTI for the wireless(e.g., CS-RNTI, TPC-CS-RNTI, TPC-PUCCH-RNTI, TPC-PUSCH-RNTI,TPC-SRS-RNTI). In an example, the wireless device may compute an RNTI(e.g., the wireless device may compute RA-RNTI based on resources usedfor transmission of a preamble). In an example, an RNTI may have asemi-statically configured value (e.g., P-RNTI or SI-RNTI). In anexample, a wireless device may monitor a group common search space whichmay be used by base station for transmitting DCIs that are intended fora group of UEs. In an example, a group common DCI may correspond to anRNTI which is commonly configured for a group of UEs. In an example, awireless device may monitor a UE-specific search space. In an example, aUE specific DCI may correspond to an RNTI configured for the wirelessdevice.

A NR system may support a single beam operation and/or a multi-beamoperation. In a multi-beam operation, a base station may perform adownlink beam sweeping to provide coverage for common control channelsand/or downlink SS blocks, which may comprise at least a PSS, a SSS,and/or PBCH. A wireless device may measure quality of a beam pair linkusing one or more RSs. One or more SS blocks, or one or more CSI-RSresources, associated with a CSI-RS resource index (CRI), or one or moreDM-RSs of PBCH, may be used as RS for measuring quality of a beam pairlink. Quality of a beam pair link may be defined as a reference signalreceived power (RSRP) value, or a reference signal received quality(RSRQ) value, and/or a CSI value measured on RS resources. The basestation may indicate whether an RS resource, used for measuring a beampair link quality, is quasi-co-located (QCLed) with DM-RSs of a controlchannel. A RS resource and DM-RSs of a control channel may be calledQCLed when a channel characteristics from a transmission on an RS to awireless device, and that from a transmission on a control channel to awireless device, are similar or same under a configured criterion. In amulti-beam operation, a wireless device may perform an uplink beamsweeping to access a cell.

In an example, a wireless device may be configured to monitor PDCCH onone or more beam pair links simultaneously depending on a capability ofa wireless device. This may increase robustness against beam pair linkblocking. A base station may transmit one or more messages to configurea wireless device to monitor PDCCH on one or more beam pair links indifferent PDCCH OFDM symbols. For example, a base station may transmithigher layer signaling (e.g. RRC signaling) or MAC CE comprisingparameters related to the Rx beam setting of a wireless device formonitoring PDCCH on one or more beam pair links. A base station maytransmit indication of spatial QCL assumption between an DL RS antennaport(s) (for example, cell-specific CSI-RS, or wireless device-specificCSI-RS, or SS block, or PBCH with or without DM-RSs of PBCH), and DL RSantenna port(s) for demodulation of DL control channel. Signaling forbeam indication for a PDCCH may be MAC CE signaling, or RRC signaling,or DCI signaling, or specification-transparent and/or implicit method,and combination of these signaling methods.

For reception of unicast DL data channel, a base station may indicatespatial QCL parameters between DL RS antenna port(s) and DM-RS antennaport(s) of DL data channel. The base station may transmit DCI (e.g.downlink grants) comprising information indicating the RS antennaport(s). The information may indicate RS antenna port(s) which may beQCL-ed with the DM-RS antenna port(s). Different set of DM-RS antennaport(s) for a DL data channel may be indicated as QCL with different setof the RS antenna port(s).

FIG. 9A is an example of beam sweeping in a DL channel. In anRRC_INACTIVE state or RRC_IDLE state, a wireless device may assume thatSS blocks form an SS burst 940, and an SS burst set 950. The SS burstset 950 may have a given periodicity. For example, in a multi-beamoperation, a base station 120 may transmit SS blocks in multiple beams,together forming a SS burst 940. One or more SS blocks may betransmitted on one beam. If multiple SS bursts 940 are transmitted withmultiple beams, SS bursts together may form SS burst set 950.

A wireless device may further use CSI-RS in the multi-beam operation forestimating a beam quality of a links between a wireless device and abase station. A beam may be associated with a CSI-RS. For example, awireless device may, based on a RSRP measurement on CSI-RS, report abeam index, as indicated in a CRI for downlink beam selection, andassociated with a RSRP value of a beam. A CSI-RS may be transmitted on aCSI-RS resource including at least one of one or more antenna ports, oneor more time or frequency radio resources. A CSI-RS resource may beconfigured in a cell-specific way by common RRC signaling, or in awireless device-specific way by dedicated RRC signaling, and/or L1/L2signaling. Multiple wireless devices covered by a cell may measure acell-specific CSI-RS resource. A dedicated subset of wireless devicescovered by a cell may measure a wireless device-specific CSI-RSresource.

A CSI-RS resource may be transmitted periodically, or using aperiodictransmission, or using a multi-shot or semi-persistent transmission. Forexample, in a periodic transmission in FIG. 9A, a base station 120 maytransmit configured CSI-RS resources 940 periodically using a configuredperiodicity in a time domain. In an aperiodic transmission, a configuredCSI-RS resource may be transmitted in a dedicated time slot. In amulti-shot or semi-persistent transmission, a configured CSI-RS resourcemay be transmitted within a configured period. Beams used for CSI-RStransmission may have different beam width than beams used for SS-blockstransmission.

FIG. 9B is an example of a beam management procedure in an example newradio network. A base station 120 and/or a wireless device 110 mayperform a downlink L1/L2 beam management procedure. One or more of thefollowing downlink L1/L2 beam management procedures may be performedwithin one or more wireless devices 110 and one or more base stations120. In an example, a P-1 procedure 910 may be used to enable thewireless device 110 to measure one or more Transmission (Tx) beamsassociated with the base station 120 to support a selection of a firstset of Tx beams associated with the base station 120 and a first set ofRx beam(s) associated with a wireless device 110. For beamforming at abase station 120, a base station 120 may sweep a set of different TXbeams. For beamforming at a wireless device 110, a wireless device 110may sweep a set of different Rx beams. In an example, a P-2 procedure920 may be used to enable a wireless device 110 to measure one or moreTx beams associated with a base station 120 to possibly change a firstset of Tx beams associated with a base station 120. A P-2 procedure 920may be performed on a possibly smaller set of beams for beam refinementthan in the P-1 procedure 910. A P-2 procedure 920 may be a special caseof a P-1 procedure 910. In an example, a P-3 procedure 930 may be usedto enable a wireless device 110 to measure at least one Tx beamassociated with a base station 120 to change a first set of Rx beamsassociated with a wireless device 110.

A wireless device 110 may transmit one or more beam management reportsto a base station 120. In one or more beam management reports, awireless device 110 may indicate some beam pair quality parameters,comprising at least, one or more beam identifications; RSRP; PrecodingMatrix Indicator (PMI)/Channel Quality Indicator (CQI)/Rank Indicator(RI) of a subset of configured beams. Based on one or more beammanagement reports, a base station 120 may transmit to a wireless device110 a signal indicating that one or more beam pair links are one or moreserving beams. A base station 120 may transmit PDCCH and PDSCH for awireless device 110 using one or more serving beams.

In an example embodiment, new radio network may support a BandwidthAdaptation (BA). In an example, receive and/or transmit bandwidthsconfigured by an UE employing a BA may not be large. For example, areceive and/or transmit bandwidths may not be as large as a bandwidth ofa cell. Receive and/or transmit bandwidths may be adjustable. Forexample, a UE may change receive and/or transmit bandwidths, e.g., toshrink during period of low activity to save power. For example, a UEmay change a location of receive and/or transmit bandwidths in afrequency domain, e.g. to increase scheduling flexibility. For example,a UE may change a subcarrier spacing, e.g. to allow different services.

In an example embodiment, a subset of a total cell bandwidth of a cellmay be referred to as a Bandwidth Part (BWP). A base station mayconfigure a UE with one or more BWPs to achieve a BA. For example, abase station may indicate, to a UE, which of the one or more(configured) BWPs is an active BWP.

FIG. 10 is an example diagram of 3 BWPs configured: BWP1 (1010 and 1050)with a width of 40 MHz and subcarrier spacing of 15 kHz; BWP2 (1020 and1040) with a width of 10 MHz and subcarrier spacing of 15 kHz; BWP3 1030with a width of 20 MHz and subcarrier spacing of 60 kHz.

In an example, a UE, configured for operation in one or more BWPs of acell, may be configured by one or more higher layers (e.g. RRC layer)for a cell a set of one or more BWPs (e.g., at most four BWPs) forreceptions by the UE (DL BWP set) in a DL bandwidth by at least oneparameter DL-BWP and a set of one or more BWPs (e.g., at most four BWPs)for transmissions by a UE (UL BWP set) in an UL bandwidth by at leastone parameter UL-BWP for a cell.

To enable BA on the PCell, a base station may configure a UE with one ormore UL and DL BWP pairs. To enable BA on SCells (e.g., in case of CA),a base station may configure a UE at least with one or more DL BWPs(e.g., there may be none in an UL).

In an example, an initial active DL BWP may be defined by at least oneof a location and number of contiguous PRBs, a subcarrier spacing, or acyclic prefix, for a control resource set for at least one common searchspace. For operation on the PCell, one or more higher layer parametersmay indicate at least one initial UL BWP for a random access procedure.If a UE is configured with a secondary carrier on a primary cell, the UEmay be configured with an initial BWP for random access procedure on asecondary carrier.

In an example, for unpaired spectrum operation, a UE may expect that acenter frequency for a DL BWP may be same as a center frequency for a ULBWP.

For example, for a DL BWP or an UL BWP in a set of one or more DL BWPsor one or more UL BWPs, respectively, a base statin may semi-staticallyconfigure a UE for a cell with one or more parameters indicating atleast one of following: a subcarrier spacing; a cyclic prefix; a numberof contiguous PRBs; an index in the set of one or more DL BWPs and/orone or more UL BWPs; a link between a DL BWP and an UL BWP from a set ofconfigured DL BWPs and UL BWPs; a DCI detection to a PDSCH receptiontiming; a PDSCH reception to a HARQ-ACK transmission timing value; a DCIdetection to a PUSCH transmission timing value; an offset of a first PRBof a DL bandwidth or an UL bandwidth, respectively, relative to a firstPRB of a bandwidth.

In an example, for a DL BWP in a set of one or more DL BWPs on a PCell,a base station may configure a UE with one or more control resource setsfor at least one type of common search space and/or one UE-specificsearch space. For example, a base station may not configure a UE withouta common search space on a PCell, or on a PSCell, in an active DL BWP.

For an UL BWP in a set of one or more UL BWPs, a base station mayconfigure a UE with one or more resource sets for one or more PUCCHtransmissions.

In an example, if a DCI comprises a BWP indicator field, a BWP indicatorfield value may indicate an active DL BWP, from a configured DL BWP set,for one or more DL receptions. If a DCI comprises a BWP indicator field,a BWP indicator field value may indicate an active UL BWP, from aconfigured UL BWP set, for one or more UL transmissions.

In an example, for a PCell, a base station may semi-statically configurea UE with a default DL BWP among configured DL BWPs. If a UE is notprovided a default DL BWP, a default BWP may be an initial active DLBWP.

In an example, a base station may configure a UE with a timer value fora PCell. For example, a UE may start a timer, referred to as BWPinactivity timer, when a UE detects a DCI indicating an active DL BWP,other than a default DL BWP, for a paired spectrum operation or when aUE detects a DCI indicating an active DL BWP or UL BWP, other than adefault DL BWP or UL BWP, for an unpaired spectrum operation. The UE mayincrement the timer by an interval of a first value (e.g., the firstvalue may be 1 millisecond or 0.5 milliseconds) if the UE does notdetect a DCI during the interval for a paired spectrum operation or foran unpaired spectrum operation. In an example, the timer may expire whenthe timer is equal to the timer value. A UE may switch to the default DLBWP from an active DL BWP when the timer expires.

In an example, a base station may semi-statically configure a UE withone or more BWPs. A UE may switch an active BWP from a first BWP to asecond BWP in response to receiving a DCI indicating the second BWP asan active BWP and/or in response to an expiry of BWP inactivity timer(for example, the second BWP may be a default BWP). For example, FIG. 10is an example diagram of 3 BWPs configured, BWP1 (1010 and 1050), BWP2(1020 and 1040), and BWP3 (1030). BWP2 (1020 and 1040) may be a defaultBWP. BWP1 (1010) may be an initial active BWP. In an example, a UE mayswitch an active BWP from BWP1 1010 to BWP2 1020 in response to anexpiry of BWP inactivity timer. For example, a UE may switch an activeBWP from BWP2 1020 to BWP3 1030 in response to receiving a DCIindicating BWP3 1030 as an active BWP. Switching an active BWP from BWP31030 to BWP2 1040 and/or from BWP2 1040 to BWP1 1050 may be in responseto receiving a DCI indicating an active BWP and/or in response to anexpiry of BWP inactivity timer.

In an example, if a UE is configured for a secondary cell with a defaultDL BWP among configured DL BWPs and a timer value, UE procedures on asecondary cell may be same as on a primary cell using the timer valuefor the secondary cell and the default DL BWP for the secondary cell.

In an example, if a base station configures a UE with a first active DLBWP and a first active UL BWP on a secondary cell or carrier, a UE mayemploy an indicated DL BWP and an indicated UL BWP on a secondary cellas a respective first active DL BWP and first active UL BWP on asecondary cell or carrier.

FIG. 11A and FIG. 11B show packet flows employing a multi connectivity(e.g. dual connectivity, multi connectivity, tight interworking, and/orthe like). FIG. 11A is an example diagram of a protocol structure of awireless device 110 (e.g. UE) with CA and/or multi connectivity as peran aspect of an embodiment. FIG. 11B is an example diagram of a protocolstructure of multiple base stations with CA and/or multi connectivity asper an aspect of an embodiment. The multiple base stations may comprisea master node, MN 1130 (e.g. a master node, a master base station, amaster gNB, a master eNB, and/or the like) and a secondary node, SN 1150(e.g. a secondary node, a secondary base station, a secondary gNB, asecondary eNB, and/or the like). A master node 1130 and a secondary node1150 may co-work to communicate with a wireless device 110.

When multi connectivity is configured for a wireless device 110, thewireless device 110, which may support multiple reception/transmissionfunctions in an RRC connected state, may be configured to utilize radioresources provided by multiple schedulers of a multiple base stations.Multiple base stations may be inter-connected via a non-ideal or idealbackhaul (e.g. Xn interface, X2 interface, and/or the like). A basestation involved in multi connectivity for a certain wireless device mayperform at least one of two different roles: a base station may eitheract as a master base station or as a secondary base station. In multiconnectivity, a wireless device may be connected to one master basestation and one or more secondary base stations. In an example, a masterbase station (e.g. the MN 1130) may provide a master cell group (MCG)comprising a primary cell and/or one or more secondary cells for awireless device (e.g. the wireless device 110). A secondary base station(e.g. the SN 1150) may provide a secondary cell group (SCG) comprising aprimary secondary cell (PSCell) and/or one or more secondary cells for awireless device (e.g. the wireless device 110).

In multi connectivity, a radio protocol architecture that a beareremploys may depend on how a bearer is setup. In an example, threedifferent type of bearer setup options may be supported: an MCG bearer,an SCG bearer, and/or a split bearer. A wireless device mayreceive/transmit packets of an MCG bearer via one or more cells of theMCG, and/or may receive/transmits packets of an SCG bearer via one ormore cells of an SCG. Multi-connectivity may also be described as havingat least one bearer configured to use radio resources provided by thesecondary base station. Multi-connectivity may or may not beconfigured/implemented in some of the example embodiments.

In an example, a wireless device (e.g. Wireless Device 110) may transmitand/or receive: packets of an MCG bearer via an SDAP layer (e.g. SDAP1110), a PDCP layer (e.g. NR PDCP 1111), an RLC layer (e.g. MN RLC1114), and a MAC layer (e.g. MN MAC 1118); packets of a split bearer viaan SDAP layer (e.g. SDAP 1110), a PDCP layer (e.g. NR PDCP 1112), one ofa master or secondary RLC layer (e.g. MN RLC 1115, SN RLC 1116), and oneof a master or secondary MAC layer (e.g. MN MAC 1118, SN MAC 1119);and/or packets of an SCG bearer via an SDAP layer (e.g. SDAP 1110), aPDCP layer (e.g. NR PDCP 1113), an RLC layer (e.g. SN RLC 1117), and aMAC layer (e.g. MN MAC 1119).

In an example, a master base station (e.g. MN 1130) and/or a secondarybase station (e.g. SN 1150) may transmit/receive: packets of an MCGbearer via a master or secondary node SDAP layer (e.g. SDAP 1120, SDAP1140), a master or secondary node PDCP layer (e.g. NR PDCP 1121, NR PDCP1142), a master node RLC layer (e.g. MN RLC 1124, MN RLC 1125), and amaster node MAC layer (e.g. MN MAC 1128); packets of an SCG bearer via amaster or secondary node SDAP layer (e.g. SDAP 1120, SDAP 1140), amaster or secondary node PDCP layer (e.g. NR PDCP 1122, NR PDCP 1143), asecondary node RLC layer (e.g. SN RLC 1146, SN RLC 1147), and asecondary node MAC layer (e.g. SN MAC 1148); packets of a split bearervia a master or secondary node SDAP layer (e.g. SDAP 1120, SDAP 1140), amaster or secondary node PDCP layer (e.g. NR PDCP 1123, NR PDCP 1141), amaster or secondary node RLC layer (e.g. MN RLC 1126, SN RLC 1144, SNRLC 1145, MN RLC 1127), and a master or secondary node MAC layer (e.g.MN MAC 1128, SN MAC 1148).

In multi connectivity, a wireless device may configure multiple MACentities: one MAC entity (e.g. MN MAC 1118) for a master base station,and other MAC entities (e.g. SN MAC 1119) for a secondary base station.In multi-connectivity, a configured set of serving cells for a wirelessdevice may comprise two subsets: an MCG comprising serving cells of amaster base station, and SCGs comprising serving cells of a secondarybase station. For an SCG, one or more of following configurations may beapplied: at least one cell of an SCG has a configured UL CC and at leastone cell of a SCG, named as primary secondary cell (PSCell, PCell ofSCG, or sometimes called PCell), is configured with PUCCH resources;when an SCG is configured, there may be at least one SCG bearer or oneSplit bearer; upon detection of a physical layer problem or a randomaccess problem on a PSCell, or a number of NR RLC retransmissions hasbeen reached associated with the SCG, or upon detection of an accessproblem on a PSCell during a SCG addition or a SCG change: an RRCconnection re-establishment procedure may not be triggered, ULtransmissions towards cells of an SCG may be stopped, a master basestation may be informed by a wireless device of a SCG failure type, forsplit bearer, a DL data transfer over a master base station may bemaintained; an NR RLC acknowledged mode (AM) bearer may be configuredfor a split bearer; PCell and/or PSCell may not be de-activated; PSCellmay be changed with a SCG change procedure (e.g. with security keychange and a RACH procedure); and/or a bearer type change between asplit bearer and a SCG bearer or simultaneous configuration of a SCG anda split bearer may or may not supported.

With respect to interaction between a master base station and asecondary base stations for multi-connectivity, one or more of thefollowing may be applied: a master base station and/or a secondary basestation may maintain RRM measurement configurations of a wirelessdevice; a master base station may (e.g. based on received measurementreports, traffic conditions, and/or bearer types) may decide to requesta secondary base station to provide additional resources (e.g. servingcells) for a wireless device; upon receiving a request from a masterbase station, a secondary base station may create/modify a containerthat may result in configuration of additional serving cells for awireless device (or decide that the secondary base station has noresource available to do so); for a UE capability coordination, a masterbase station may provide (a part of) an AS configuration and UEcapabilities to a secondary base station; a master base station and asecondary base station may exchange information about a UE configurationby employing of RRC containers (inter-node messages) carried via Xnmessages; a secondary base station may initiate a reconfiguration of thesecondary base station existing serving cells (e.g. PUCCH towards thesecondary base station); a secondary base station may decide which cellis a PSCell within a SCG; a master base station may or may not changecontent of RRC configurations provided by a secondary base station; incase of a SCG addition and/or a SCG SCell addition, a master basestation may provide recent (or the latest) measurement results for SCGcell(s); a master base station and secondary base stations may receiveinformation of SFN and/or subframe offset of each other from OAM and/orvia an Xn interface, (e.g. for a purpose of DRX alignment and/oridentification of a measurement gap). In an example, when adding a newSCG SCell, dedicated RRC signaling may be used for sending requiredsystem information of a cell as for CA, except for a SFN acquired from aMIB of a PSCell of a SCG.

FIG. 12 is an example diagram of a random access procedure. One or moreevents may trigger a random access procedure. For example, one or moreevents may be at least one of following: initial access from RRC_IDLE,RRC connection re-establishment procedure, handover, DL or UL dataarrival during RRC_CONNECTED when UL synchronization status isnon-synchronized, transition from RRC_Inactive, and/or request for othersystem information. For example, a PDCCH order, a MAC entity, and/or abeam failure indication may initiate a random access procedure.

In an example embodiment, a random access procedure may be at least oneof a contention based random access procedure and a contention freerandom access procedure. For example, a contention based random accessprocedure may comprise, one or more Msg 1 1220 transmissions, one ormore Msg2 1230 transmissions, one or more Msg3 1240 transmissions, andcontention resolution 1250. For example, a contention free random accessprocedure may comprise one or more Msg 1 1220 transmissions and one ormore Msg2 1230 transmissions.

In an example, a base station may transmit (e.g., unicast, multicast, orbroadcast), to a UE, a RACH configuration 1210 via one or more beams.The RACH configuration 1210 may comprise one or more parametersindicating at least one of following: available set of PRACH resourcesfor a transmission of a random access preamble, initial preamble power(e.g., random access preamble initial received target power), an RSRPthreshold for a selection of a SS block and corresponding PRACHresource, a power-ramping factor (e.g., random access preamble powerramping step), random access preamble index, a maximum number ofpreamble transmission, preamble group A and group B, a threshold (e.g.,message size) to determine the groups of random access preambles, a setof one or more random access preambles for system information requestand corresponding PRACH resource(s), if any, a set of one or more randomaccess preambles for beam failure recovery request and correspondingPRACH resource(s), if any, a time window to monitor RA response(s), atime window to monitor response(s) on beam failure recovery request,and/or a contention resolution timer.

In an example, the Msg1 1220 may be one or more transmissions of arandom access preamble. For a contention based random access procedure,a UE may select a SS block with a RSRP above the RSRP threshold. Ifrandom access preambles group B exists, a UE may select one or morerandom access preambles from a group A or a group B depending on apotential Msg3 1240 size. If a random access preambles group B does notexist, a UE may select the one or more random access preambles from agroup A. A UE may select a random access preamble index randomly (e.g.with equal probability or a normal distribution) from one or more randomaccess preambles associated with a selected group. If a base stationsemi-statically configures a UE with an association between randomaccess preambles and SS blocks, the UE may select a random accesspreamble index randomly with equal probability from one or more randomaccess preambles associated with a selected SS block and a selectedgroup.

For example, a UE may initiate a contention free random access procedurebased on a beam failure indication from a lower layer. For example, abase station may semi-statically configure a UE with one or morecontention free PRACH resources for beam failure recovery requestassociated with at least one of SS blocks and/or CSI-RSs. If at leastone of SS blocks with a RSRP above a first RSRP threshold amongstassociated SS blocks or at least one of CSI-RSs with a RSRP above asecond RSRP threshold amongst associated CSI-RSs is available, a UE mayselect a random access preamble index corresponding to a selected SSblock or CSI-RS from a set of one or more random access preambles forbeam failure recovery request.

For example, a UE may receive, from a base station, a random accesspreamble index via PDCCH or RRC for a contention free random accessprocedure. If a base station does not configure a UE with at least onecontention free PRACH resource associated with SS blocks or CSI-RS, theUE may select a random access preamble index. If a base stationconfigures a UE with one or more contention free PRACH resourcesassociated with SS blocks and at least one SS block with a RSRP above afirst RSRP threshold amongst associated SS blocks is available, the UEmay select the at least one SS block and select a random access preamblecorresponding to the at least one SS block. If a base station configuresa UE with one or more contention free PRACH resources associated withCSI-RSs and at least one CSI-RS with a RSRP above a second RSPRthreshold amongst the associated CSI-RSs is available, the UE may selectthe at least one CSI-RS and select a random access preamblecorresponding to the at least one CSI-RS.

A UE may perform one or more Msg1 1220 transmissions by transmitting theselected random access preamble. For example, if a UE selects an SSblock and is configured with an association between one or more PRACHoccasions and one or more SS blocks, the UE may determine an PRACHoccasion from one or more PRACH occasions corresponding to a selected SSblock. For example, if a UE selects a CSI-RS and is configured with anassociation between one or more PRACH occasions and one or more CSI-RSs,the UE may determine a PRACH occasion from one or more PRACH occasionscorresponding to a selected CSI-RS. A UE may transmit, to a basestation, a selected random access preamble via a selected PRACHoccasions. A UE may determine a transmit power for a transmission of aselected random access preamble at least based on an initial preamblepower and a power-ramping factor. A UE may determine a RA-RNTIassociated with a selected PRACH occasions in which a selected randomaccess preamble is transmitted. For example, a UE may not determine aRA-RNTI for a beam failure recovery request. A UE may determine anRA-RNTI at least based on an index of a first OFDM symbol and an indexof a first slot of a selected PRACH occasions, and/or an uplink carrierindex for a transmission of Msg1 1220.

In an example, a UE may receive, from a base station, a random accessresponse, Msg 2 1230. A UE may start a time window (e.g., ra-ResponseWindow) to monitor a random access response. For beam failure recoveryrequest, a base station may configure a UE with a different time window(e.g., bfr-Response Window) to monitor response on beam failure recoveryrequest. For example, a UE may start a time window (e.g., ra-ResponseWindow or bfr-Response Window) at a start of a first PDCCH occasionafter a fixed duration of one or more symbols from an end of a preambletransmission. If a UE transmits multiple preambles, the UE may start atime window at a start of a first PDCCH occasion after a fixed durationof one or more symbols from an end of a first preamble transmission. AUE may monitor a PDCCH of a cell for at least one random access responseidentified by a RA-RNTI or for at least one response to beam failurerecovery request identified by a C-RNTI while a timer for a time windowis running.

In an example, a UE may consider a reception of random access responsesuccessful if at least one random access response comprises a randomaccess preamble identifier corresponding to a random access preambletransmitted by the UE. A UE may consider the contention free randomaccess procedure successfully completed if a reception of random accessresponse is successful. If a contention free random access procedure istriggered for a beam failure recovery request, a UE may consider acontention free random access procedure successfully complete if a PDCCHtransmission is addressed to a C-RNTI. In an example, if at least onerandom access response comprises a random access preamble identifier, aUE may consider the random access procedure successfully completed andmay indicate a reception of an acknowledgement for a system informationrequest to upper layers. If a UE has signaled multiple preambletransmissions, the UE may stop transmitting remaining preambles (if any)in response to a successful reception of a corresponding random accessresponse.

In an example, a UE may perform one or more Msg 3 1240 transmissions inresponse to a successful reception of random access response (e.g., fora contention based random access procedure). A UE may adjust an uplinktransmission timing based on a timing advanced command indicated by arandom access response and may transmit one or more transport blocksbased on an uplink grant indicated by a random access response.Subcarrier spacing for PUSCH transmission for Msg3 1240 may be providedby at least one higher layer (e.g. RRC) parameter. A UE may transmit arandom access preamble via PRACH and Msg3 1240 via PUSCH on a same cell.A base station may indicate an UL BWP for a PUSCH transmission of Msg31240 via system information block. A UE may employ HARQ for aretransmission of Msg 3 1240.

In an example, multiple UEs may perform Msg 1 1220 by transmitting asame preamble to a base station and receive, from the base station, asame random access response comprising an identity (e.g., TC-RNTI).Contention resolution 1250 may ensure that a UE does not incorrectly usean identity of another UE. For example, contention resolution 1250 maybe based on C-RNTI on PDCCH or a UE contention resolution identity onDL-SCH. For example, if a base station assigns a C-RNTI to a UE, the UEmay perform contention resolution 1250 based on a reception of a PDCCHtransmission that is addressed to the C-RNTI. In response to detectionof a C-RNTI on a PDCCH, a UE may consider contention resolution 1250successful and may consider a random access procedure successfullycompleted. If a UE has no valid C-RNTI, a contention resolution may beaddressed by employing a TC-RNTI. For example, if a MAC PDU issuccessfully decoded and a MAC PDU comprises a UE contention resolutionidentity MAC CE that matches the CCCH SDU transmitted in Msg3 1250, a UEmay consider the contention resolution 1250 successful and may considerthe random access procedure successfully completed.

FIG. 13 is an example structure for MAC entities as per an aspect of anembodiment. In an example, a wireless device may be configured tooperate in a multi-connectivity mode. A wireless device in RRC_CONNECTEDwith multiple RX/TX may be configured to utilize radio resourcesprovided by multiple schedulers located in a plurality of base stations.The plurality of base stations may be connected via a non-ideal or idealbackhaul over the Xn interface. In an example, a base station in aplurality of base stations may act as a master base station or as asecondary base station. A wireless device may be connected to one masterbase station and one or more secondary base stations. A wireless devicemay be configured with multiple MAC entities, e.g. one MAC entity formaster base station, and one or more other MAC entities for secondarybase station(s). In an example, a configured set of serving cells for awireless device may comprise two subsets: an MCG comprising servingcells of a master base station, and one or more SCGs comprising servingcells of a secondary base station(s). FIG. 13 illustrates an examplestructure for MAC entities when MCG and SCG are configured for awireless device.

In an example, at least one cell in a SCG may have a configured UL CC,wherein a cell of at least one cell may be called PSCell or PCell ofSCG, or sometimes may be simply called PCell. A PSCell may be configuredwith PUCCH resources. In an example, when a SCG is configured, there maybe at least one SCG bearer or one split bearer. In an example, upondetection of a physical layer problem or a random access problem on aPSCell, or upon reaching a number of RLC retransmissions associated withthe SCG, or upon detection of an access problem on a PSCell during a SCGaddition or a SCG change: an RRC connection re-establishment proceduremay not be triggered, UL transmissions towards cells of an SCG may bestopped, a master base station may be informed by a UE of a SCG failuretype and DL data transfer over a master base station may be maintained.

In an example, a MAC sublayer may provide services such as data transferand radio resource allocation to upper layers (e.g. 1310 or 1320). A MACsublayer may comprise a plurality of MAC entities (e.g. 1350 and 1360).A MAC sublayer may provide data transfer services on logical channels.To accommodate different kinds of data transfer services, multiple typesof logical channels may be defined. A logical channel may supporttransfer of a particular type of information. A logical channel type maybe defined by what type of information (e.g., control or data) istransferred. For example, BCCH, PCCH, CCCH and DCCH may be controlchannels and DTCH may be a traffic channel. In an example, a first MACentity (e.g. 1310) may provide services on PCCH, BCCH, CCCH, DCCH, DTCHand MAC control elements. In an example, a second MAC entity (e.g. 1320)may provide services on BCCH, DCCH, DTCH and MAC control elements.

A MAC sublayer may expect from a physical layer (e.g. 1330 or 1340)services such as data transfer services, signaling of HARQ feedback,signaling of scheduling request or measurements (e.g. CQI). In anexample, in dual connectivity, two MAC entities may be configured for awireless device: one for MCG and one for SCG. A MAC entity of wirelessdevice may handle a plurality of transport channels. In an example, afirst MAC entity may handle first transport channels comprising a PCCHof MCG, a first BCH of MCG, one or more first DL-SCHs of MCG, one ormore first UL-SCHs of MCG and one or more first RACHs of MCG. In anexample, a second MAC entity may handle second transport channelscomprising a second BCH of SCG, one or more second DL-SCHs of SCG, oneor more second UL-SCHs of SCG and one or more second RACHs of SCG.

In an example, if a MAC entity is configured with one or more SCells,there may be multiple DL-SCHs and there may be multiple UL-SCHs as wellas multiple RACHs per MAC entity. In an example, there may be one DL-SCHand UL-SCH on a SpCell. In an example, there may be one DL-SCH, zero orone UL-SCH and zero or one RACH for an SCell. A DL-SCH may supportreceptions using different numerologies and/or TTI duration within a MACentity. A UL-SCH may also support transmissions using differentnumerologies and/or TTI duration within the MAC entity.

In an example, a MAC sublayer may support different functions and maycontrol these functions with a control (e.g. 1355 or 1365) element.Functions performed by a MAC entity may comprise mapping between logicalchannels and transport channels (e.g., in uplink or downlink),multiplexing (e.g. 1352 or 1362) of MAC SDUs from one or differentlogical channels onto transport blocks (TB) to be delivered to thephysical layer on transport channels (e.g., in uplink), demultiplexing(e.g. 1352 or 1362) of MAC SDUs to one or different logical channelsfrom transport blocks (TB) delivered from the physical layer ontransport channels (e.g., in downlink), scheduling information reporting(e.g., in uplink), error correction through HARQ in uplink or downlink(e.g. 1363), and logical channel prioritization in uplink (e.g. 1351 or1361). A MAC entity may handle a random access process (e.g. 1354 or1364).

FIG. 14 is an example diagram of a RAN architecture comprising one ormore base stations. In an example, a protocol stack (e.g. RRC, SDAP,PDCP, RLC, MAC, and PHY) may be supported at a node. A base station(e.g. gNB 120A or 120B) may comprise a base station central unit (CU)(e.g. gNB-CU 1420A or 1420B) and at least one base station distributedunit (DU) (e.g. gNB-DU 1430A, 1430B, 1430C, or 1430D) if a functionalsplit is configured. Upper protocol layers of a base station may belocated in a base station CU, and lower layers of the base station maybe located in the base station DUs. An F1 interface (e.g. CU-DUinterface) connecting a base station CU and base station DUs may be anideal or non-ideal backhaul. F1-C may provide a control plane connectionover an F1 interface, and F1-U may provide a user plane connection overthe F1 interface. In an example, an Xn interface may be configuredbetween base station CUs.

In an example, a base station CU may comprise an RRC function, an SDAPlayer, and a PDCP layer, and base station DUs may comprise an RLC layer,a MAC layer, and a PHY layer. In an example, various functional splitoptions between a base station CU and base station DUs may be possibleby locating different combinations of upper protocol layers (RANfunctions) in a base station CU and different combinations of lowerprotocol layers (RAN functions) in base station DUs. A functional splitmay support flexibility to move protocol layers between a base stationCU and base station DUs depending on service requirements and/or networkenvironments.

In an example, functional split options may be configured per basestation, per base station CU, per base station DU, per UE, per bearer,per slice, or with other granularities. In per base station CU split, abase station CU may have a fixed split option, and base station DUs maybe configured to match a split option of a base station CU. In per basestation DU split, a base station DU may be configured with a differentsplit option, and a base station CU may provide different split optionsfor different base station DUs. In per UE split, a base station (basestation CU and at least one base station DUs) may provide differentsplit options for different wireless devices. In per bearer split,different split options may be utilized for different bearers. In perslice splice, different split options may be applied for differentslices.

FIG. 15 is an example diagram showing RRC state transitions of awireless device. In an example, a wireless device may be in at least oneRRC state among an RRC connected state (e.g. RRC_Connected 1530,RRC_Connected), an RRC idle state (e.g. RRC_Idle 1510, RRC_Idle), and/oran RRC inactive state (e.g. RRC_Inactive 1520, RRC_Inactive). In anexample, in an RRC connected state, a wireless device may have at leastone RRC connection with at least one base station (e.g. gNB and/or eNB),which may have a UE context of the wireless device. A UE context (e.g. awireless device context) may comprise at least one of an access stratumcontext, one or more radio link configuration parameters, bearer (e.g.data radio bearer (DRB), signaling radio bearer (SRB), logical channel,QoS flow, PDU session, and/or the like) configuration information,security information, PHY/MAC/RLC/PDCP/SDAP layer configurationinformation, and/or the like configuration information for a wirelessdevice. In an example, in an RRC idle state, a wireless device may nothave an RRC connection with a base station, and a UE context of awireless device may not be stored in a base station. In an example, inan RRC inactive state, a wireless device may not have an RRC connectionwith a base station. A UE context of a wireless device may be stored ina base station, which may be called as an anchor base station (e.g. lastserving base station).

In an example, a wireless device may transition a UE RRC state betweenan RRC idle state and an RRC connected state in both ways (e.g.connection release 1540 or connection establishment 1550; or connectionreestablishment) and/or between an RRC inactive state and an RRCconnected state in both ways (e.g. connection inactivation 1570 orconnection resume 1580). In an example, a wireless device may transitionits RRC state from an RRC inactive state to an RRC idle state (e.g.connection release 1560).

In an example, an anchor base station may be a base station that maykeep a UE context (a wireless device context) of a wireless device atleast during a time period that a wireless device stays in a RANnotification area (RNA) of an anchor base station, and/or that awireless device stays in an RRC inactive state. In an example, an anchorbase station may be a base station that a wireless device in an RRCinactive state was lastly connected to in a latest RRC connected stateor that a wireless device lastly performed an RNA update procedure in.In an example, an RNA may comprise one or more cells operated by one ormore base stations. In an example, a base station may belong to one ormore RNAs. In an example, a cell may belong to one or more RNAs.

In an example, a wireless device may transition a UE RRC state from anRRC connected state to an RRC inactive state in a base station. Awireless device may receive RNA information from the base station. RNAinformation may comprise at least one of an RNA identifier, one or morecell identifiers of one or more cells of an RNA, a base stationidentifier, an IP address of the base station, an AS context identifierof the wireless device, a resume identifier, and/or the like.

In an example, an anchor base station may broadcast a message (e.g. RANpaging message) to base stations of an RNA to reach to a wireless devicein an RRC inactive state, and/or the base stations receiving the messagefrom the anchor base station may broadcast and/or multicast anothermessage (e.g. paging message) to wireless devices in their coveragearea, cell coverage area, and/or beam coverage area associated with theRNA through an air interface.

In an example, when a wireless device in an RRC inactive state movesinto a new RNA, the wireless device may perform an RNA update (RNAU)procedure, which may comprise a random access procedure by the wirelessdevice and/or a UE context retrieve procedure. A UE context retrieve maycomprise: receiving, by a base station from a wireless device, a randomaccess preamble; and fetching, by a base station, a UE context of thewireless device from an old anchor base station. Fetching may comprise:sending a retrieve UE context request message comprising a resumeidentifier to the old anchor base station and receiving a retrieve UEcontext response message comprising the UE context of the wirelessdevice from the old anchor base station.

In an example embodiment, a wireless device in an RRC inactive state mayselect a cell to camp on based on at least a on measurement results forone or more cells, a cell where a wireless device may monitor an RNApaging message and/or a core network paging message from a base station.In an example, a wireless device in an RRC inactive state may select acell to perform a random access procedure to resume an RRC connectionand/or to transmit one or more packets to a base station (e.g. to anetwork). In an example, if a cell selected belongs to a different RNAfrom an RNA for a wireless device in an RRC inactive state, the wirelessdevice may initiate a random access procedure to perform an RNA updateprocedure. In an example, if a wireless device in an RRC inactive statehas one or more packets, in a buffer, to transmit to a network, thewireless device may initiate a random access procedure to transmit oneor more packets to a base station of a cell that the wireless deviceselects. A random access procedure may be performed with two messages(e.g. 2 stage random access) and/or four messages (e.g. 4 stage randomaccess) between the wireless device and the base station.

In an example embodiment, a base station receiving one or more uplinkpackets from a wireless device in an RRC inactive state may fetch a UEcontext of a wireless device by transmitting a retrieve UE contextrequest message for the wireless device to an anchor base station of thewireless device based on at least one of an AS context identifier, anRNA identifier, a base station identifier, a resume identifier, and/or acell identifier received from the wireless device. In response tofetching a UE context, a base station may transmit a path switch requestfor a wireless device to a core network entity (e.g. AMF, MME, and/orthe like). A core network entity may update a downlink tunnel endpointidentifier for one or more bearers established for the wireless devicebetween a user plane core network entity (e.g. UPF, S-GW, and/or thelike) and a RAN node (e.g. the base station), e.g. changing a downlinktunnel endpoint identifier from an address of the anchor base station toan address of the base station.

A gNB may communicate with a wireless device via a wireless networkemploying one or more new radio technologies. The one or more radiotechnologies may comprise at least one of: multiple technologies relatedto physical layer; multiple technologies related to medium accesscontrol layer; and/or multiple technologies related to radio resourcecontrol layer. Example embodiments of enhancing the one or more radiotechnologies may improve performance of a wireless network. Exampleembodiments may increase the system throughput, or data rate oftransmission. Example embodiments may reduce battery consumption of awireless device. Example embodiments may improve latency of datatransmission between a gNB and a wireless device. Example embodimentsmay improve network coverage of a wireless network. Example embodimentsmay improve transmission efficiency of a wireless network.

Random access (RA) procedures may be used to establish communicationsbetween a wireless device and a base station in a cell. Prior toinitiation of a RA procedure, a base station may transmit one or moreRRC messages to configure the wireless device with one or moreparameters of RACH configuration. The base station may broadcast ormulticast the one or more RRC messages to one or more wireless devices.The one or more RRC messages may be wireless device-specific messages,e.g., dedicated RRC messages transmitted to a wireless device inRRC_INACTIVE 1520 or RRC_CONNECTED 1530. The one or more RRC messagesmay comprise one or more parameters required for transmitting at leastone preamble via one or more random access resources. For example, theone or more parameters may indicate at least one of the following: PRACHresource allocation, preamble format, SSB information (e.g., totalnumber of SSBs, downlink resource allocation of SSB transmission,transmission power of SSB transmission, and/or other information),and/or uplink radio resources for one or more transport blocktransmissions.

A base station may transmit one or more downlink reference signals. Forexample, one or more downlink reference signals may comprise one or morediscovery reference signals. A wireless device may select a firstdownlink reference signal among the one or more downlink referencesignals. For example, the first downlink reference signal may compriseone or more synchronization signals and a physical broadcast channel(SS/PBCH). For example, the wireless device may adjust a downlinksynchronization based on the one or more synchronization signals. Forexample, the one or more downlink reference signals may comprise one ormore channel state information-reference signals (CSI-RS).

One or more RRC messages may further comprise one or more parametersindicating one or more downlink control channels, for example, PDDCH.Each of the one or more downlink control channels may be associated withat least one of the one or more downlink reference signals. For example,the first downlink reference signal may comprise one or more systeminformation (e.g., master information block (MIB) and/or systeminformation block (SIB)). A base station may transmit the one or moresystem information, for example, on a physical broadcast channel (PBCH),a physical downlink control channel (PDCCH), and/or a physical downlinkshared channel (PDSCH).

One or more system information may comprise at least one informationelement (e.g., PDCCH-Config, PDCCH-ConfigSIB1, PDCCH-ConfigCommon). Theat least one information element may be used, for example, to configurea wireless device with, among other things, one or more controlparameters. The one or more control parameters may comprise one or moreparameters of one or more control resource sets (CORESET). For example,the one or more control parameters may comprise the parameters of afirst common CORESET#0 (controlResourceSetZero), and/or a first commonCORESET (commonControlResourceSet). The one or more control parametersmay further comprise one or more search space sets. For example, the oneor more control parameters may comprise the parameters of a first searchspace for the system information block (searchSpaceSIB1), and/or a firstcommon search space#0 (searchSpaceZero), and/or a first random accesssearch space (ra-SearchSpace), and/or a first paging search space(pagingSearchSpace). For example, the wireless device may use the one ormore control parameters to acquire the one or more downlink controlchannels.

For example, a wireless device may monitor a set of candidates for theone or more downlink control channels in the one or more controlresource sets. The one or more control resource sets may be on a firstactive downlink frequency band, e.g., an active bandwidth part (BWP), ona first activated serving cell. For example, the first activated servingcell may be configured with the one or more control parameters accordingto the one or more search space sets. For example, the wireless devicemay decode each of the one or more downlink control channels in the setof candidates for the one or more downlink control channels according toa first format of a first downlink control information (DCI). Forexample, the set of candidates for the one or more downlink controlchannels may be defined in terms of the one or more search space sets.For example, the one or more search space sets may be one or more commonsearch space sets (e.g., Type0-PDCCH, Type0A-PDCCH, Type1-PDCCH,Type2-PDCCH, Type3-PDCCH), and/or one or more wireless device-specificsearch space sets.

For example, a wireless device may monitor a set of candidates for theone or more downlink control channels in a Type0-PDCCH common searchspace set. For example, a Type0-PDCCH common search space set may beconfigured by at least one information element, e.g., PDCCH-ConfigSIB1in a MIB. For example, the Type0-PDCCH common search space set may beconfigured by one or more search space sets, e.g., a searchSpaceSIB1 inPDCCH-ConfigCommon, or searchSpaceZero in PDCCH-ConfigCommon. Forexample, the Type0-PDCCH common search space set may be configured for afirst format of a first downlink control information scrambled by afirst radio network temporary identifier, e.g., a systeminformation-radio network temporary identifier (SI-RNTI).

For example, a wireless device may monitor a set of candidates for oneor more downlink control channels in a Type1-PDCCH common search spaceset. For example, the Type1-PDCCH common search space set may beconfigured by one or more search space sets, e.g., a ra-searchSpace in aPDCCH-ConfigCommon. For example, the Type1-PDCCH common search space setmay be configured for a second format of a second downlink controlinformation scrambled by a second radio network temporary identifier,e.g., a random access-radio network temporary identifier (RA-RNTI), or atemporary cell-radio network temporary identifier (TC-RNTI).

A wireless device may determine, for example during a cell search, thata first control resource set for a first common search space (e.g.,Type0-PDCCH) is present. The first control resource set may comprise oneor more resource blocks and one or more symbols. One or more RRCmessages may comprise one or more parameters indicating one or moremonitoring occasions of the one or more downlink control channels. Forexample, the wireless device may determine a number of consecutiveresource blocks and a number of consecutive symbols for the firstcontrol resource set of the first common search space. For example, oneor more bits (e.g., a four most significant bits) of the at least oneinformation element (e.g., PDCCH-ConfigSIB1) may indicate the number ofconsecutive resource blocks and the number of consecutive symbols. Forexample, the wireless device may determine the one or more monitoringoccasions of the one or more downlink control channels from one or morebits (e.g., a four least significant bits) of the at least oneinformation element (e.g., PDCCH-ConfigSIB1). For example, the one ormore monitoring occasions of the one or more downlink control channelsassociated with the first downlink reference signal may be determinedbased on one or more system frame numbers and one or more slot indexesof the first control resource set. For example, the first downlinkreference signal with a first index may overlap in time with the firstframe number and the first slot index.

A wireless device may determine a first downlink channel among the oneor more downlink control channels, based on a first downlink referencesignal. For example, the first downlink channel may be a first downlinkcontrol channel, or a first system information block (e.g., SIB1). Thewireless device may assume that a demodulation reference signal antennaport associated with a reception of the first downlink channel is quasico-located (QCL) with the first downlink reference signal. For example,the demodulation reference signal antenna port associated with thereception of the first downlink channel and the first downlink referencesignal (e.g., the corresponding SS/PBCH block) may be quasi co-locatedwith respect to at least one of the following: an average gain,QCL-TypeA, and/or QCL-TypeD.

A physical layer of the wireless device may receive from higher layers,among other information, one or more SS/PBCH block indexes. For example,the physical layer may receive one or more configuration parameters ofone or more physical random access channel (PRACH) transmissionparameters (e.g., the one or more PRACH transmission parameters mayindicate PRACH preamble format, preamble index, a corresponding RA-RNTI,time resources, and/or frequency resources for PRACH transmission),and/or parameters for determining one or more sequences and their shiftsin the PRACH preamble sequence set (e.g., set type). The physical layermay provide to higher layers one or more corresponding sets of referencesignal received power (RSRP) measurements.

A random access procedure may comprise one or more transmissions of arandom access preamble (e.g., Msg1) in one or more PRACH occasions. Therandom access procedure may further comprise one or more transmissionsof one or more random access response (RAR) messages, for example, withone or more physical downlink channels (e.g., Msg2). The random accessprocedure may further comprise one or more Msg3 in one or more physicaluplink channels (e.g., PUSCH), and one or more physical downlinkchannels (PDSCH) for contention resolution. The random access proceduremay be triggered upon request of one or more PRACH transmissions, forexample, by higher layers or by one or more control orders (e.g., PDCCHorder).

A MAC entity of the wireless device may select one or more random accessresources for a random access procedure initiated. The MAC entity mayselect a first downlink reference signal. For example, the MAC entitymay select the first downlink reference signal (e.g., a first SS/PBCHblock (SSB), or a first channel state information-reference signal(CSI-RS)) with the first reference signal received power (RSRP) above afirst reference signal received power threshold. For example, the firstreference signal received power threshold may be defined per a type ofreference signal (e.g., rsrp-ThresholdSSB may for a SSB, andrsrp-ThresholdCSI-RS for a CSI-RS). The first reference signal receivedpower threshold may be broadcast, semi-statically configured, and/orpredefined. For example, the MAC entity may select the first downlinkreference signal for contention-free random access procedure, forexample for beam failure recovery, or system information request. Forexample, the MAC entity may select the first downlink reference signalfor contention-based random access procedure.

A wireless device may select one or more random access resources. Theone or more random access resources may, for example, comprise one ormore random access preambles, one or more time resources, and/or one ormore frequency resources for PRACH transmission. The one or more randomaccess resources may be predefined. The one or more random accessresources may be provided by one or more RRC messages. The one or morerandom access resources may be provided by one or more downlink controlorders (e.g., PDCCH order). The one or more random access resources maybe determined based on the first downlink reference signal. For example,the wireless device may set a first preamble index to a parameter (e.g.,ra-PreambleIndex) corresponding to the first downlink reference signal.

A wireless device may transmit at least one random access preamble inone or more random access resources. For example, the wireless devicemay transmit a first preamble with a first preamble index. The firstpreamble may be transmitted using a first PRACH format with a firsttransmission power on one or more PRACH resources. The one or more PRACHresources may comprise one or more PRACH occasions.

One or more RRC messages may comprise one or more random accessparameters. For example, a cell specific random access configurationmessage (e.g., RACH-ConfigCommon and/or RACH-ConfigGeneric) maycomprise, among other parameters, at least one of following: a totalnumber of random access preambles (e.g., totalNumberOfRA-Preambles), oneor more PRACH configuration index (e.g., prach-ConfigurationIndex), anumber of PRACH occasions that may be multiplexed in frequency domain(FDMed) in a time instance (e.g., msg1-FDM), an offset of a lowest PRACHoccasion in frequency domain with respect to a first resource block(e.g., msg1-FrequencyStart), a power ramping step for PRACH (e.g.,powerRampingStep), a target power level at the network receiver side(preambleReceivedTargetPower), a maximum number of random accesspreamble transmission that may be performed (e.g., preambleTransMax), awindow length for a random access response (i.e., RAR, e.g., Msg2)(e.g., ra-ResponseWindow), a number of SSBs per random access channel(RACH) occasion and a number of contention-based preambles per SSB(e.g., ssb-perRACH-OccasionAndCB-PreamblesPerSSB). For example, thetotal number of random access preambles may be a multiple of the numberof SSBs per RACH occasion. For example, the window length for RAR may bein number of slots. For example, a dedicated random access configurationmessage (e.g., RACH-ConfigDedicated) may comprise, among otherparameters, one or more RACH occasions for contention-free random access(e.g., occasions), and one or more PRACH mask index for random accessresource selection (e.g., ra-ssb-OccasionMaskIndex).

One or more random access parameters (e.g.,ssb-perRACH-OccasionAndCB-PreamblesPerSSB) may provide a wireless devicewith a first number (e.g., N) of one or more downlink reference signals(e.g., SS/PBCH blocks) that may be associated with a first PRACHoccasion. The one or more random access parameters (e.g.,ssb-perRACH-OccasionAndCB-PreamblesPerSSB) may provide the wirelessdevice with a second number (e.g., R) of the one or more random accesspreambles for a first downlink reference signal and for a first PRACHoccasion. The one or more random access preambles may be contentionbased preambles. The first downlink reference signal may be a firstSS/PBCH block. For example, according to the first number (e.g., ifN<1), the first SS/PBCH block may be mapped to at least one (e.g., 1/N)consecutive valid PRACH occasions. For example, according to the secondnumber (e.g., R), at least one preamble with consecutive indexesassociated with the first SS/PBCH block may start from the firstpreamble index for the first valid PRACH occasion.

For example, one or more PRACH configuration indexes (e.g.,prach-ConfigurationIndex), may indicate, among other things, a preambleformat, a periodicity for one or more PRACH time resources, one or morePRACH subframe numbers, a number of PRACH slots within the one or morePRACH subframes, a PRACH starting symbol number, and a number of timedomain PRACH occasions within first PRACH slot.

One or more random access parameters may further comprise an associationperiod for mapping one or more SS/PBCH blocks to one or more PRACHoccasions. For example, one or more SS/PBCH block indexes may be mappedto the one or more PRACH occasions based on an order. For example, theorder may be as follows: In increasing order of indexes of at least onepreamble in a first PRACH occasion. In increasing order of indexes ofone or more frequency resources (e.g., for frequency multiplexed PRACHoccasions). In increasing order of indexes of one or more time resources(e.g., for time multiplexed PRACH occasions) in the first PRACH slot. Inincreasing order of indexes for one or more PRACH slots.

A base station may trigger a PRACH transmission by transmitting one ormore control orders (e.g., PDCCH order). One or more PRACH mask indexes(e.g., ra-ssb-OccasionMaskIndex) may indicate one or more PRACHoccasions. The one or more PRACH occasions may be associated with afirst SS/PBCH block index indicated by the one or more control orders.The one or more PRACH occasions may be mapped (e.g., consecutively) forthe first SS/PBCH block index. The wireless device may select a firstPRACH occasion indicated by a first PRACH mask index value for the firstSS/PBCH block index in the first association period. The firstassociation period may be a first mapping cycle. The wireless device mayreset the one or more indexes of the one or more PRACH occasions for thefirst mapping cycle.

A wireless device may determine a first PRACH occasion for transmittinga first preamble. The wireless device may determine a randomaccess-radio network temporary identifier (e.g., RA-RNTI) associatedwith the first PRACH occasion. The a random access-radio networktemporary identifier may be, among other things, a function of at leastone of PRACH symbol, and a slot index of a PRACH occasion in a systemframe, and a frequency index of the PRACH occasion in frequency domain,and an uplink carrier index. For example, the random access-radionetwork temporary identifier may be computed as:RA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id. For example,s_id may be a PRACH starting symbol, t_id may be an index of a firstslot of a first PRACH occasion I a system frame, f_id may be an index ofthe first PRACH occasion in frequency domain, and ul_carrier_id may bean uplink carrier index.

A wireless device may determine a parameter indicating a first preambletarget power (e.g., PREAMBLE_RECEIVED_TARGET_POWER). The wireless devicemay transmit a first preamble using a first PRACH occasion, with a firstpreamble transmission power (e.g., P_(PRACH,b,f,c)(i)). The firstpreamble transmission power may be determined based on the firstpreamble target power.

In response to a PRACH transmission, a wireless device may receive oneor more random access responses (RARs) (e.g., Msg2). The one or morerandom access responses may be scrambled by a particular radio networktemporary identifier (e.g., RA-RNTI). The wireless device may monitor asearch space set (e.g., the Type1-PDCCH common search space) for a firstdownlink control information (e.g., DCI format 1_0). The first downlinkcontrol information may comprise the one or more RARs. For example, abase station may transmit the one or more RARs in a form of DCI format1_0 for a random access procedure initiated by PDCCH order, MAC layer,and/or RRC layer. For example, the DCI format 1_0 may comprise at leastone of the following fields: one or more random access preamble index,SS/PBCH index, PRACH mask index, UL/SUL indicator, frequency and timedomain resource assignments, modulation and/or coding schemes.

A wireless device may monitor for a first downlink control information(e.g., DCI format 1_0) during a time window. The time window may beindicated by the one or more RRC messages. The time window may start ata first symbol of a first control resource set. The wireless device maybe configured by the one or more parameters in the one or more RRCmessages to receive the first downlink control information on the firstcontrol resource set. The wireless device may determine a length of thetime window based on the one or more parameters in the one or more RRCmessages (e.g., ra-ResponseWindow). The length of the time window may bein number of slots.

A wireless device may stop a time window after or in response to areception of one or more random access responses being determined assuccessful. A reception of the one or more random access responses maybe determined as successful, for example, when the one or more randomaccess responses comprise a preamble index (e.g., a random accesspreamble identity: RAPID) corresponding to a preamble that the wirelessdevice transmits to a base station. For example, the RAPID may beassociated with the PRACH transmission. The one or more random accessresponses may comprise an uplink grant indicating one or more uplinkresources granted for the wireless device. The wireless device maytransmit one or more transport blocks (e.g., Message 3) via the one ormore uplink resources.

In an example, a gNB may transmit a DCI via a PDCCH for at least one of:scheduling assignment/grant; slot format notification; pre-emptionindication; and/or power-control commends. More specifically, the DCImay comprise at least one of: identifier of a DCI format; downlinkscheduling assignment(s); uplink scheduling grant(s); slot formatindicator; pre-emption indication; power-control for PUCCH/PUSCH; and/orpower-control for SRS.

In an example, a downlink scheduling assignment DCI may compriseparameters indicating at least one of: identifier of a DCI format; PDSCHresource indication; transport format; HARQ information; controlinformation related to multiple antenna schemes; and/or a command forpower control of the PUCCH.

In an example, an uplink scheduling grant DCI may comprise parametersindicating at least one of: identifier of a DCI format; PUSCH resourceindication; transport format; HARQ related information; and/or a powercontrol command of the PUSCH.

In an example, different types of control information may correspond todifferent DCI message sizes. For example, supporting multiple beamsand/or spatial multiplexing in the spatial domain and noncontiguousallocation of RBs in the frequency domain may require a largerscheduling message, in comparison with an uplink grant allowing forfrequency-contiguous allocation. DCI may be categorized into differentDCI formats, where a format corresponds to a certain message size and/orusage.

In an example, a wireless device may monitor one or more PDCCH fordetecting one or more DCI with one or more DCI format, in common searchspace or wireless device-specific search space. In an example, awireless device may monitor PDCCH with a limited set of DCI format, tosave power consumption. The more DCI format to be detected, the morepower be consumed at the wireless device.

In an example, the information in the DCI formats for downlinkscheduling may comprise at least one of: identifier of a DCI format;carrier indicator; frequency domain resource assignment; time domainresource assignment; bandwidth part indicator; HARQ process number; oneor more MCS; one or more NDI; one or more RV; MIMO related information;Downlink assignment index (DAI); PUCCH resource indicator;PDSCH-to-HARQ_feedback timing indicator; TPC for PUCCH; SRS request; andpadding if necessary. In an example, the MIMO related information maycomprise at least one of: PMI; precoding information; transport blockswap flag; power offset between PDSCH and reference signal;reference-signal scrambling sequence; number of layers; and/or antennaports for the transmission; and/or Transmission Configuration Indication(TCI).

In an example, the information in the DCI formats used for uplinkscheduling may comprise at least one of: an identifier of a DCI format;carrier indicator; bandwidth part indication; resource allocation type;frequency domain resource assignment; time domain resource assignment;MCS; NDI; Phase rotation of the uplink DMRS; precoding information; CSIrequest; SRS request; Uplink index/DAI; TPC for PUSCH; and/or padding ifnecessary.

In an example, a gNB may perform CRC scrambling for a DCI, beforetransmitting the DCI via a PDCCH. The gNB may perform CRC scrambling bybinary addition of multiple bits of at least one wireless deviceidentifier (e.g., C-RNTI, CS-RNTI, TPC-CS-RNTI, TPC-PUCCH-RNTI,TPC-PUSCH-RNTI, SP CSI C-RNTI, or TPC-SRS-RNTI) and the CRC bits of theDCI. The wireless device may check the CRC bits of the DCI, whendetecting the DCI. The wireless device may receive the DCI when the CRCis scrambled by a sequence of bits that is the same as the at least onewireless device identifier.

In an example, in order to support wide bandwidth operation, a gNB maytransmit one or more PDCCH in different control resource sets(coresets). A gNB may transmit one or more RRC message comprisingconfiguration parameters of one or more coresets. A coreset may compriseat least one of: a first OFDM symbol; a number of consecutive OFDMsymbols; a set of resource blocks; a CCE-to-REG mapping. In an example,a gNB may transmit a PDCCH in a dedicated coreset for particularpurpose, for example, for beam failure recovery confirmation.

In an example, a wireless device may monitor PDCCH for detecting DCI inone or more configured coresets, to reduce the power consumption.

In an example, a DCI format (e.g., DCI format 1_0) may be used for ascheduling of PDSCH in one DL cell. The DCI format for downlinkscheduling may comprise CRC bits scrambled by at least one wirelessdevice identifier (e.g., C-RNTI, CS-RNTI, or MCS-C-RNTI). Theinformation in the DCI format for downlink scheduling may comprise atleast one of: identifier of a DCI format; frequency domain resourceassignment; time domain resource assignment; VRB-to-PRB mapping;modulation and coding scheme; new data indicator; redundancy version;HARQ process number; downlink assignment index; TPC command forscheduled PUCCH; PUCCH resource indicator; and/or PDSCH-to-HARQ_feedbacktiming indicator.

In an example, a DCI format for downlink scheduling may be for randomaccess procedure initiated by a PDCCH order. For example, the CRC bitsof the DCI format for downlink scheduling may be scrambled by a firstradio network temporary identifier (e.g., C-RNTI), and the frequencydomain resource assignment field may be a first value (e.g., all ones),indicating that the DCI format is for random access procedure. Theinformation in the DCI format may then comprise at least one of:identifier for DCI format; frequency domain resource assignments; randomaccess preamble index; UL/SUL indicator; SS/PBCH index; PRACH maskindex; and/or reserved bits. The random access preamble index field mayindicate a preamble sequence to be used for the random access procedure.The SS/PBCH index field may indicate the SS/PBCH (SSB) that may be usedto determine one or more RACH occasions for the PRACH transmission. ThePRACH mask index field may indicate the one or more RACH occasionsassociated with the SS/PBCH indicated by the SS/PBCH index for PRACHtransmission.

A random access procedure may be initiated by a PDCCH order, or by a MACentity, or by RRC. There may be only one random access procedure ongoingat a time in a MAC entity. The random access procedure on an SCell mayonly be initiated by the PDCCH order with a first random access preambleindex field, wherein the first random access preamble index field maynot be all zeros. For example, when a new random access procedure istriggered while another is already ongoing in the MAC entity, it may beup to a wireless device implementation whether to continue with theongoing procedure or start with the new procedure (e.g. for SI request).

A wireless device may receive one or more RRC messages for a randomaccess procedure comprising at least one of parameters: PRACHconfiguration index (prach-ConfigurationIndex; one or more PRACHoccasions for a transmission of a random access preamble); initialrandom access preamble power (preambleReceivedTargetPower); a list ofone or more reference signals (CSI-RS and/or SSB) identifying one ormore candidate beams for recovery and/or the random access parameters(candidateBeamRSList); RSRP threshold for selection of a referencedownlink signal (e.g., SSB, and/or CSI-RS); a search space identity formonitoring a response of a beam failure recovery request; apower-ramping factor (powerRampingStep); a scaling factor for aprioritized random access procedure (scalingFactorBI); a random accesspreamble (ra-PreambleIndex); an association between the one or morePRACH occasions and the reference signal (CSI-RS and/or SSB:ra-ssb-OccasionMaskIndex/ra-OccasionList); a maximum number of randomaccess preamble transmission (reambleTransMax); and/or a first number ofSSBs mapped to each one of the one or more PRACH occasions and a secondnumber of contention-based random access preambles mapped to each one ofthe one or more SSBs (ssb-perRACH-OccasionAndCB-PreamblesPerSSB). Atleast one of the following wireless device variables may be used for therandom access procedure: preamble index (PREAMBLE_INDEX); preambletransmission counter (PREAMBLE_TRANSMISSION_COUNTER); transmission powerramping counter (PREAMBLE_POWER_RAMPING_COUNTER); preamble power rampingstep (PREAMBLE_POWER_RAMPING_STEP); preamble received target power(PREAMBLE_RECEIVED_TARGET_POWER); preamble backoff (PREAMBLE_BACKOFF);maximum transmission power (PCMAX); scaling factor for backoff indicator(SCALING_FACTOR_BI); and/or temporary identifier (TC-RNTI).

In an example, a random access procedure may be initiated on a servingcell. A MAC entity of a wireless device may initialize one or morerandom access parameters. The wireless device may then perform a randomaccess resource selection procedure.

In an example, a random access procedure may be initiated by a PDCCHorder. The PDCCH order may comprise a random access preamble index. Thewireless device may set the preamble index to the random access preambleindex signaled by the PDCCH order. The wireless device may select an SSBsignaled by the PDCCH order.

In an example, a contention-free random access procedure may beinitiated, wherein a wireless device receives one or more messagescomprising parameters of contention-free random access resources. Thecontention-free random access resources may be associated with one ormore reference signals (CSI-RS and/or SSB), wherein at least onereference signal of the one or more reference signals may have RSRPabove a threshold. The wireless device may select a reference signal(CSI-RS and/or SSB) amongst the at least one reference signals with RSRPabove the threshold. The wireless device may set a preamble index to arandom access preamble index corresponding to the reference signal(CSI-RS and/or SSB).

In an example, a contention-based random access procedure may beinitiated, wherein a wireless device receives one or more messagescomprising parameters of contention-based random access resources. Thewireless device may select an SSB from one or more SSBs, wherein the oneor more SSBs have RSRP above a threshold, or may select any SSB. Thewireless device may select a random access preamble, for examplerandomly with equal probability, from one or more random accesspreambles associated with the SSB.

A wireless device may determine a first PRACH occasion from one or morePRACH occasions corresponding to a first SSB or a first CSI-RS. Forexample, the first SSB may be quasi-colocated with the first CSI-RS. Forexample, the one or more PRACH occasions may be configured by RRCmessages comprising parameters indicating an association between the oneor more PRACH occasions and the first SSB or the first CSI-RS. Forexample, the one or more random access occasions may be indicated byPDCCH. A MAC entity of the wireless device may select a PRACH occasion,for example randomly with equal probability, amongst one or moreconsecutive PRACH occasions corresponding to the first SSB or the firstCSI-RS. The MAC entity may consider a possible occurrence of measurementgaps when determining the first PRACH occasion from the one or morePRACH occasions corresponding to the first SSB or the first CSI-RS. Thewireless device may then perform a random access preamble transmissionprocedure.

A MAC entity of a wireless device may perform a random access preambletransmission procedure for each one of one or more random accesspreambles. The MAC entity may increment a preamble power ramping counter(PREAMBLE_POWER_RAMPING_COUNTER) by one. The MAC entity may select adelta preamble value (DELTA_PREAMBLE) for a power offset. The MAC entitymay set a preamble received target power(PREAMBLE_RECEIVED_TARGET_POWER) topreambleReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_POWER_RAMPING_COUNTER−1)×PREAMBLE_POWER_RAMPING_STEP,wherein the parameters of preamble transmission power are configured asdescribed above. The wireless device may determine a random access radionetwork temporary identifier (RA-RNTI) associated with a first PRACHoccasion in which the random access preamble is transmitted. The RA-RNTIassociated with the first PRACH occasion in which the random accesspreamble is transmitted is computed as:RA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id, where s_id isan index of a first OFDM symbol of the first PRACH occasion (0≤s_id≤14),t_id is an index of a first slot of the first PRACH occasion in a systemframe (0≤t_id≤80), f_id is an index of the first PRACH occasion in thefrequency domain (0≤fid<8), and ul_carrier_id is an UL carrier used forRandom Access Preamble transmission (0 for NUL carrier, and 1 for SULcarrier). The MAC entity may instruct the physical layer to transmit therandom access preamble via the first PRACH occasion, correspondingRA-RNTI, preamble index (PREAMBLE_INDEX), andPREAMBLE_RECEIVED_TARGET_POWER. Once a random access preamble istransmitted, a MAC entity may start a random access response window(ra-ResponseWindow) configured by RRC at a first PDCCH occasion. The MACentity may monitor the PDCCH for random access response(s) (RAR)identified by the corresponding RA-RNTI, for example, while the randomaccess response window is running. The MAC entity may receive a downlinkassignment (the RAR message) on the PDCCH for the RA-RNTI and maysuccessfully decode the received TB. The random access response (RARmessage) may comprise a MAC subPDU with a random access preambleidentifier corresponding to the preamble index (PREAMBLE_INDEX), and mayconsider the RAR reception successful. The RAR message may comprise atiming advance command. The MAC entity may process the timing advancecommand and may consider the random access procedure successfullycompleted, for example, for a contention-free random access procedure.For a contention-based random access procedure, the RAR message maycomprise an UL grant, and the MAC entity may proceed with transmissionof Msg3 for contention resolution.

In RRC_CONNECTED state, the network may control wireless devicemobility. For example, the network may decide when the wireless deviceconnects to which cell(s) (e.g., E-UTRA cell(s), and/or NR cell(s),and/or inter-RAT cell(s)). Cell level mobility may require explicit RRCsignaling to be triggered, e.g., handover. For network controlledmobility in cell level in RRC_CONNECTED, the PCell may be changed usingan RRC Connection Reconfiguration message. The SCell(s) may be changedusing the RRC Connection Reconfiguration message. For inter-BS handover,as shown in FIG. 16, the signaling procedure may comprise at least oneof the following: Handover Request; Handover Request Acknowledgement;Handover Command; Random Access and Handover Complete. A source basestation (BS) may initiate handover and send, to a target BS, a HandoverRequest over a network interface (e.g., Xn and/or X2). The target BS mayperform an admission control and provide a RRC configuration as part ofthe Handover Acknowledgement. The source BS may provide the RRCconfiguration to the wireless device in the Handover Command. Thehandover command message may comprise cell ID and all informationrequired to access the target cell. The wireless device may access thetarget cell and may not need to read the system information of thetarget cell. For example, the information required for contention-basedand contention-free random access can be included in the HandoverCommand message. The access information to the target cell may comprisebeam specific information, if any. The wireless device may move the RRCconnection to the target BS via initiating a random access procedure.The wireless device may reply the Handover Complete message to thetarget BS. The wireless deice may also send user data if a grant isavailable.

The radio access network handover may perform the preparation andexecution phase of the handover procedure without involvement of thecore network, e.g., preparation messages may be directly exchangedbetween BSs. The target BS may trigger the release of the resources atthe source BS during the handover completion phase.

The network may trigger the handover procedure, e.g., based on radioconditions, load, QoS, wireless device category/capability, and/or thelike. To facilitate this, the network may configure the wireless deviceto perform measurement reporting (possibly including the configurationof measurement gaps). The network may also initiate handover blindly,for example, without having received measurement reports from thewireless device.

Before sending the handover message to the wireless device, the sourceBS may prepare one or more target cells. The source BS may select thetarget PCell. The source BS may also provide the target BS with a listof best cells on each frequency for which measurement information isavailable, for example, in order of decreasing RSRP. The source BS mayalso include available measurement information for the cells provided inthe list. The target BS may decide which SCells are configured for useafter handover, which may include cells other than the ones indicated bythe source BS.

According to some of the various aspects of embodiments, the target BSmay generate a message used to configure the wireless device for thehandover. For example, the message may include the access stratumconfiguration to be used in the target cell(s). The source BS maytransparently (for example, does not alter values/content) forward thehandover message/information received from the target BS to the wirelessdevice. When appropriate, the source BS may initiate data forwarding for(a subset of) the dedicated radio bearers. After receiving the handovermessage, the wireless device may attempt to access the target PCell atthe available RACH occasion according to a random access resourceselection. When allocating a dedicated preamble for the random access inthe target PCell, the network (e.g., NR and/or E-UTRA) may ensure thepreamble is available from the first RACH occasion the wireless devicemay use. Upon successful completion of the handover, the wireless devicemay send a message used to confirm the handover to the target BS.

According to some of the various aspects of embodiments, if the targetBS does not support the release of RRC protocol which the source BS usedto configure the wireless device, the target BS may be unable tocomprehend the wireless device configuration provided by the source BS.In this case, the target BS may use the full configuration option toreconfigure the wireless device for handover and re-establishment. Fullconfiguration option includes an initialization of the radioconfiguration, which makes the procedure independent of theconfiguration used in the source cell(s) with the exception that thesecurity algorithms are continued for the RRC re-establishment.

According to some of the various aspects of embodiments, the handovermechanism triggered by RRC may require the wireless device to reset theMAC entity and reestablish RLC. RRC managed handovers with and withoutPDCP entity re-establishment may both be supported. After the successfulcompletion of handover, PDCP SDUs may be re-transmitted in the targetcell(s). This may apply for dedicated radio bearers using RLC-AM modeand/or for handovers not involving full configuration option. For DRBsusing RLC AM mode, PDCP may either be re-established together with asecurity key change or initiate a data recovery procedure without a keychange. For DRBs using RLC UM mode and for SRBs, PDCP may either bere-established together with a security key change or remain as it iswithout a key change. Data forwarding, in-sequence delivery andduplication avoidance at handover may be guaranteed when the target BSuses the same DRB configuration as the source BS. After the successfulcompletion of handover not involving full configuration option, the SN(sequence number) and/or the HFN (hyper frame number) may be reset forsome radio bearers. For the dedicated radio bearers using RLC-AM modeboth SN and HFN may continue. For reconfigurations involving the fullconfiguration option, the PDCP entities may be newly established (SN andHFN may not continue) for dedicated radio bearers irrespective of theRLC mode. The wireless device behavior to be performed upon handover maybe the same regardless of the handover procedures used within thenetwork (e.g. whether the handover includes X2/Xn or N2/S1 signalingprocedures).

The network may support timer based handover failure procedure. RRCconnection re-establishment procedure may be used for recovering fromhandover failure. The source BS may, for some time, maintain a contextto enable the wireless device to return in case of handover failure.After having detected handover failure, the wireless device may attemptto resume the RRC connection either in the source PCell or in anothercell using the RRC re-establishment procedure. This connectionresumption may succeed if the accessed cell is prepared. For example,when the access cell is a cell of the source BS or of another BS towardswhich handover preparation has been performed. The cell in which there-establishment procedure succeeds becomes the PCell while SCells, ifconfigured, may be released.

Normal measurement and mobility procedures may be used to supporthandover to cells broadcasting a CSG (closed subscriber group) identity.In addition, a network (e.g., E-UTRAN/NR) may configure the wirelessdevice to report that it is entering or leaving the proximity of cell(s)included in its CSG whitelist. a network (e.g., E-UTRAN/NR) may requestthe wireless device to provide additional information broadcast by thehandover candidate cell e.g. cell global identity, CSG identity, CSGmembership status. A network (e.g., E-UTRAN/NR) may use the proximityreport to configure measurements as well as to decide whether or not torequest additional information broadcast by the handover candidate cell.The additional information may be used to verify whether or not thewireless device is authorized to access the target PCell and may also beneeded to identify handover candidate cell. This may involve resolvingPCI confusion, for example, when the physical layer identity that isincluded in the measurement report may not uniquely identify the cell.

The purpose of RRC connection reconfiguration procedure may be to modifyan RRC connection, e.g. to establish, modify and/or release RB s, toperform handover, to setup, modify, and/or release measurements, to add,modify, and/or release SCells. As part of the procedure, NAS dedicatedinformation may be transferred from a network (e.g., E-UTRAN/NR) to thewireless device. If the received RRC Connection Reconfiguration messageincludes the sCellToReleaseList, the wireless device performs SCellrelease. If the received RRC Connection Reconfiguration message includesthe sCellToAddModList, the wireless device performs SCell additions ormodification.

The wireless device context within the source BS may compriseinformation regarding roaming/handover/access restrictions which may beprovided either at connection establishment or at the last TA(registration/tracking area) update process. The source BS may configurethe wireless device measurement procedures employing at least one RRCconnection reconfiguration message. The wireless device may be triggeredto send at least one measurement report by the rules set by, forexample, system information, RRC configuration, and/or the like. Thesource BS may make a handover decision based on many parameters, forexample, the measurement reports, RRM information, traffic and load, acombination of the above, and/or the like. The source BS may initiatethe handover procedure by sending a handover request message to one ormore potential target BSs. When the source BS sends the handover requestmessage, it may start a handover preparation timer. Upon reception ofthe handover request acknowledgement message the source BS may stop thehandover preparation timer.

In a network interface (e.g. X2/Xn) handover process, the source BS(e.g. eNB/gNB) may transmit a handover request message to one or morepotential target BSs to initiate the handover. The handover requestmessage may comprise a transparent RRC container with necessaryinformation to prepare the handover at the target side. In an exampleembodiment, a handover request message may comprise: a target cell ID, aC-RNTI of the wireless device in the source BS, RRM-configurationincluding wireless device inactive time, basic AS-configurationincluding antenna information and DL carrier frequency, the current QoSflow to DRB mapping rules applied to the wireless device, the SIB1 fromsource BS, the wireless device capabilities for different RATs, and PDUsession related information. In an example embodiment, handover requestmessage may further comprise the wireless device reported measurementinformation including beam-related information if available. Afterissuing a handover request, the source BS may not reconfigure thewireless device.

In a core network interface (e.g., S1/N2, and/or NG interface that maycomprise an NG user-plane part and/or an NG control-plane part) handoverprocess without AMF/MME relocation, the source BS may transmit ahandover required message to an AMF/MME for one or more potential targetBSs, and the AMF/MME may transmit a handover request message to thepotential target BSs. The handover required message and/or the handoverrequest message may pass information to prepare the handover at thetarget side. In a core network interface (e.g., S1/N2, and/or NGinterface) handover process relocating an AMF/MME, a source BS maytransmit a handover required message to a source AMF/MME for one or morepotential target BSs, the source AMF/MME may transmit a forwardrelocation request message to one or more potential target AMFs/MMEsserving the potential target BSs, and the potential target AMFs/MMEs maytransmit a handover request message to the potential target BSs. Thehandover required message, the forward relocation request message,and/or the handover request message may pass information to prepare thehandover at the target side. During the handover preparation phase, theserving BS may transmit the handover request message to one or morepotential target BSs. This information may be employed, at least inpart, by the potential target BS, for example, to configure the wirelessdevice after completing the handover.

A target BS may employ admission control in order to properly preparebefore the wireless device connects to the target BS. Handover admissioncontrol may be performed by the target BS depending on many factors,e.g., QoS required for wireless device bearers, wireless devicecapabilities, wireless device configuration, target BS load, acombination of the above, and/or the like. The target BS may configurethe required resources according to the received information from theserving (source) BS and may reserve a C-RNTI and/or a RACH preamble. Theaccess stratum configuration to be used in the target cell may bespecified independently (for example, as an establishment) or as a deltacompared to the access stratum-configuration used in the source cell(for example as a reconfiguration). Slice-aware admission control may beperformed if the slice information is sent to the target BS. The targetBS may reject PDU sessions, for example when the PDU sessions areassociated with non-supported slices.

A target BS may prepare handover with L1/L2 and may send the handoverrequest acknowledge message to the source BS. In an X2/Xn handoverprocedure, the handover request acknowledge message may include atransparent container to be sent to the wireless device as an RRCmessage to perform the handover. In an S1/N2 handover procedure withoutMME/AMF relocation, the handover request acknowledge message from thetarget BS to the MME/AMF and/or the handover command message from theMME/AMF to the source BS may include a transparent container to be sentto the wireless device as an RRC message to perform the handover. In anS1/N2 handover procedure relocating an MME/AMF, the handover requestacknowledge message from the target BS to the target MME/AMF, theforward relocation response message from the target MME/AMF to thesource MME/AMF, and/or the handover command message from the sourceMME/AMF to the source BS may include a transparent container to be sentto the wireless device as an RRC message to perform the handover. Thecontainer may include a new C-RNTI, target BS security algorithmidentifiers for the selected security algorithms, a dedicated RACHpreamble, access parameters, SIB s, and/or other configurationparameters. The target BS may generate the RRC message to perform thehandover, for example, RRC connection reconfiguration message includingthe mobility control information. The RRC message may be sent by thesource BS towards the wireless device.

The source BS may trigger the wireless device handover by sending an RRCreconfiguration message to the wireless device, comprising theinformation required to access the target cell, e.g., target cell ID,new C-RNTI, target BS security algorithm identifiers for the selectedsecurity algorithms. The RRC reconfiguration message may also compriseat least one of following: a set of dedicated RACH resources, theassociation between RACH resources and SSB(s), the association betweenRACH resources and wireless device-specific CSI-RS configuration(s),common RACH resources, and/or system information of the target cell.

The source BS may send SN status transfer message to the target BS. Thesource BS may perform the necessary integrity protection and cipheringof the message. The wireless device may receive the RRC connectionreconfiguration message from the source BS and may start performing thehandover. The wireless device may not need to delay the handoverexecution for delivering the HARQ/ARQ responses to the source BS.

After receiving the RRC connection reconfiguration message that mayinclude the mobility control information, the wireless device mayperform synchronization to the target BS and access the target cell viaRACH on the primary cell. The wireless device Random access proceduremay employ a contention-free procedure if a dedicated RACH preamble wasindicated in the RRC connection reconfiguration message. The wirelessdevice random access procedure may employ a contention-based procedureif no dedicated preamble was indicated. The wireless device may derivetarget BS specific keys and may configure the selected securityalgorithms to be used in the target cell. The target BS may respond withuplink allocation and timing advance.

After the wireless device has successfully accessed the target cell, thewireless device may complete the RRC handover procedure by sending anRRC connection reconfiguration complete message (C-RNTI) to the targetBS to confirm the handover and to indicate that the handover procedureis completed for the wireless device. The wireless device may transmit aMAC uplink Buffer Status Report (BSR) Control Element (CE) along withthe uplink RRC Connection Reconfiguration Complete message or maytransmit a MAC uplink BSR CE whenever possible to the target BS. Thetarget BS may verify the C-RNTI sent in the RRC ConnectionReconfiguration Complete message. The target BS may now begin sendingdata to the wireless device and receiving data from the wireless device.

The target BS may send a path switch request message to AMF/MME totrigger the core network (e.g., 5GC) to switch the DL data path towardsthe target BS and to establish an interface (e.g., NG-C interface)towards the target BS. The core network may switch the DL data pathtowards the target BS. The UPF may send one or more end marker packetson the old path to the source BS per PDU session/tunnel and then mayrelease any U-plane/TNL resources towards the source BS. The AMF/MME mayconfirm the path switch request message with a path switch requestacknowledgement message. Upon reception of the path switch requestacknowledgment message from the AMF/MME, the target BS may send thewireless device context release to inform the source BS about thesuccess of the handover. The source BS may then release radio andC-plane related resources associated to the wireless device context. Anyongoing data forwarding may continue.

The RRM configuration may include both beam measurement information (forlayer 3 mobility) associated to SSB(s) and CSI-RS(s) for the reportedcell(s) if both types of measurements are available. Also, if CA isconfigured, the RRM configuration may comprise the list of best cells oneach frequency for which measurement information is available. And theRRM measurement information may also comprise the beam measurement forthe listed cells that belong to the target BS.

The common RACH configuration for beams in the target cell may only beassociated to the SSB(s). The network may have dedicated RACHconfigurations associated to the SSB(s) and/or have dedicated RACHconfigurations associated to CSI-RS(s) within a cell. The target BS mayonly include one of the following RACH configurations in the HandoverCommand to enable the wireless device to access the target cell: commonRACH configuration; Common RACH configuration+Dedicated RACHconfiguration associated with SSB; Common RACH configuration+DedicatedRACH configuration associated with CSI-RS. The dedicated RACHconfiguration allocates RACH resource(s) together with a qualitythreshold to use them. When dedicated RACH resources are provided, theyare prioritized by the wireless device and the wireless device may notswitch to contention-based RACH resources as long as the qualitythreshold of those dedicated resources is met. The order to access thededicated RACH resources may be up to wireless device implementation.

As shown in FIG. 17, the wireless device may measure at least one beamof a cell (e.g., serving cell and/or neighboring non-serving cell(s)).The measurement results (e.g., RSRP values) may be averaged to derivethe cell quality. The wireless device may be configured to consider asubset of the detected beams. The wireless device may perform filteringat two different levels: at the physical layer to derive beam qualityand then at RRC level to derive cell quality from the at least on beam.Cell quality from beam measurements is derived in the same way for theserving cell(s) and for the non-serving cell(s). Measurement reports maycontain the measurement results of the X best beams if the wirelessdevice is configured to do so by the BS.

FIG. 18 demonstrates a high-level measurement model. K beams maycorrespond to the measurements on SSB and/or CSI-RS resources configuredfor L3 mobility by BS and detected by the wireless device at L1. Asshown in FIG. 18, at point A measurements (e.g., beam specific samples)may inter to the physical layer. The inputs measures at point A mayinter layer 1 filtering. The exact filtering may be implementationdependent. Measurements (e.g., beam specific measurements) may bereported by layer 1 to layer 3 after layer 1 filtering at point A¹. beamspecific measurements may be consolidated to derive cell quality. Thebehavior of the Beam consolidation/selection may be standardized and theconfiguration of this module is provided by RRC signaling. Reportingperiod at B may equal one measurement period at A1. A measurement (e.g.cell quality) derived from beam-specific measurements may be reported tolayer 3 after beam consolidation/selection at point B. Filtering may beperformed on the measurements provided at point B. The behavior of theLayer 3 filters may be standardized and the configuration of the layer 3filters may be provided by RRC signaling. Filtering reporting period atC may equal one measurement period at B. A measurement after processingin the layer 3 filter is at point C. The reporting rate is identical tothe reporting rate at point B. This measurement may be used as input forone or more evaluation of reporting criteria. The one or more evaluationof reporting criteria may check whether actual measurement reporting isnecessary at point D. The evaluation may be based on more than one flowof measurements at reference point C, e.g. to compare between differentmeasurements. This is illustrated by input C and C1. The wireless devicemay evaluate the reporting criteria at least every time a newmeasurement result is reported at point C, C1. The reporting criteriamay be standardized and the configuration is provided by RRC signaling(wireless device measurements). Measurement report information (message)may be sent on the radio interface at point D. Filtering performed onthe measurements (e.g., beam specific measurements) may be provided atpoint A1. The behavior of the beam filters may be standardized and theconfiguration of the beam filters may be provided by RRC signaling.Filtering reporting period at E may equal one measurement period at A1.A measurement (e.g. beam-specific measurement) after processing in thebeam filter is at point E. The reporting rate may be identical to thereporting rate at point A1. This measurement may be used as input forselecting the X measurements to be reported. Beam Selection for beamreporting may select the X measurements from the measurements providedat point E. The behavior of the beam selection may be standardized andthe configuration of this module may be provided by RRC signaling. Beammeasurement information may be included in measurement report (sent) onthe radio interface at point F.

Layer 1 filtering may introduce a certain level of measurementaveraging. How and when the wireless device may perform the requiredmeasurements may be implementation specific to the point that the outputat B fulfils the performance. Layer 3 filtering for cell quality andrelated parameters used may not introduce any delay in the sampleavailability between B and C. Measurement at point C, Cl may be theinput used in the event evaluation. L3 Beam filtering and relatedparameters used may not introduce any delay in the sample availabilitybetween E and F. Measurement reports may be characterized by thefollowing: Measurement reports may include the measurement identity ofthe associated measurement configuration that triggered the reporting;Cell and beam measurement quantities to be included in measurementreports may be configured by the network; The number of non-servingcells to be reported may be limited through configuration by thenetwork; Cells belonging to a blacklist configured by the network maynot be used in event evaluation and reporting, and conversely when awhitelist is configured by the network, only the cells belonging to thewhitelist may be used in event evaluation and reporting; Beammeasurements to be included in measurement reports may be configured bythe network (beam identifier only, measurement result and beamidentifier, or no beam reporting). Intra-frequency neighbor (cell)measurements and inter-frequency neighbor (cell) measurements may bedefined as follows: SSB based intra-frequency measurement: a measurementmay be defined as an SSB based intra-frequency measurement provided thecenter frequency of the SSB of the serving cell and the center frequencyof the SSB of the neighbor cell are the same, and the subcarrier spacingof the two SSBs is also the same. SSB based inter-frequency measurement:a measurement may be defined as an SSB based inter-frequency measurementprovided the center frequency of the SSB of the serving cell and thecenter frequency of the SSB of the neighbor cell are different, or thesubcarrier spacing of the two SSBs is different. For SSB basedmeasurements, one measurement object may correspond to one SSB and thewireless device may consider different SSBs as different cells. CSI-RSbased intra-frequency measurement: a measurement may be defined as aCSI-RS based intra-frequency measurement provided the bandwidth of theCSI-RS resource on the neighbor cell configured for measurement iswithin the bandwidth of the CSI-RS resource on the serving cellconfigured for measurement, and the subcarrier spacing of the two CSI-RSresources is the same. CSI-RS based inter-frequency measurement: ameasurement may be defined as a CSI-RS based inter-frequency measurementprovided the bandwidth of the CSI-RS resource on the neighbor cellconfigured for measurement is not within the bandwidth of the CSI-RSresource on the serving cell configured for measurement, or thesubcarrier spacing of the two CSI-RS resources is different.

The amount of data traffic carried over cellular networks is expected toincrease for many years to come. The number of users/devices isincreasing, and each user/device accesses an increasing number andvariety of services, e.g. video delivery, large files, images. Thisrequires not only high capacity in the network, but also provisioning ofvery high data rates to meet customer expectations on interactivity andresponsiveness. More spectrum is therefore needed for cellular operatorsto meet the increasing demand. Considering user expectations of highdata rates along with seamless mobility, it is beneficial that morespectrum be made available for deploying macro cells as well as smallcells for cellular systems.

Striving to meet the market demands, there has been increasing interestfrom operators in deploying some complementary access utilizingunlicensed spectrum to meet the traffic growth. This is exemplified bythe large number of operator-deployed Wi-Fi networks and the 3GPPstandardization of interworking solutions with Wi-Fi, e.g., LTE/WLANinterworking. This interest indicates that unlicensed spectrum, whenpresent, may be an effective complement to licensed spectrum forcellular operators to address the traffic explosion in some scenarios,such as hotspot areas. For example, licensed assisted access (LAA)and/or new radio on unlicensed band(s) (NR-U) may offer an alternativefor operators to make use of unlicensed spectrum while managing oneradio network, thus offering new possibilities for optimizing thenetwork's efficiency.

In an example embodiment, listen-before-talk (LBT) may be implementedfor transmission in an unlicensed cell. The unlicensed cell may bereferred to as a LAA cell and/or a NR-U cell. The unlicensed cell may beoperated as non-standalone with an anchor cell in a licensed band orstandalone without an anchor cell in a licensed band. LBT may comprise aclear channel assessment (CCA).

In an example embodiment, discontinuous transmission on an unlicensedband with limited maximum transmission duration may be enabled. Some ofthese functions may be supported by one or more signals to betransmitted from the beginning of a discontinuous downlink transmissionin the unlicensed band. Channel reservation may be enabled by thetransmission of signals, by an NR-U node, after or in response togaining channel access based on a successful LBT operation. Other nodesmay receive the signals (e.g., transmitted for the channel reservation)with an energy level above a certain threshold that may sense thechannel to be occupied. Functions that may need to be supported by oneor more signals for operation in unlicensed band with discontinuousdownlink transmission may comprise one or more of the following:detection of the downlink transmission in unlicensed band (includingcell identification) by wireless devices; time & frequencysynchronization of wireless devices.

In an example embodiment, downlink transmission and frame structuredesign for operation in an unlicensed band may employ subframe,(mini-)slot, and/or symbol boundary alignment according to timingrelationships across serving cells aggregated by carrier aggregation.This may not imply that base station transmissions start at thesubframe, (mini-) slot, and/or symbol boundary. Unlicensed celloperation (e.g., LAA and/or NR-U) may support transmitting PDSCH, forexample, when not all OFDM symbols are available for transmission in asubframe according to LBT. Delivery of necessary control information forthe PDSCH may also be supported.

An LBT procedure may be employed for fair and friendly coexistence of a3GPP system (e.g., LTE and/or NR) with other operators and technologiesoperating in unlicensed spectrum. For example, a node attempting totransmit on a carrier in unlicensed spectrum may perform a CCA as a partof an LBT procedure to determine if the channel is free for use. The LBTprocedure may involve energy detection to determine if the channel isbeing used. For example, regulatory requirements in some regions, e.g.,in Europe, specify an energy detection threshold such that if a nodereceives energy greater than the threshold, the node assumes that thechannel is being used and not free. While nodes may follow suchregulatory requirements, a node may optionally use a lower threshold forenergy detection than that specified by regulatory requirements. A radioaccess technology (e.g., LTE and/or NR) may employ a mechanism toadaptively change the energy detection threshold. For example, NR-U mayemploy a mechanism to adaptively lower the energy detection thresholdfrom an upper bound. An adaptation mechanism may not preclude static orsemi-static setting of the threshold. In an example Category 4 LBT (CAT4LBT) mechanism or other type of LBT mechanisms may be implemented.

Various example LBT mechanisms may be implemented. In an example, forsome signals, in some implementation scenarios, in some situations,and/or in some frequencies no LBT procedure may be performed by thetransmitting entity. In an example, Category 1 (CAT1, e.g., no LBT) maybe implemented in one or more cases. For example, a channel inunlicensed band may be hold by a first device (e.g., a base station forDL transmission), and a second device (e.g., a wireless device) takesover the for a transmission without performing the CAT1 LBT. In anexample, Category 2 (CAT2, e.g. LBT without random back-off and/orone-shot LBT) may be implemented. The duration of time determining thatthe channel is idle may be deterministic (e.g., by a regulation). A basestation may transmit an uplink grant indicating a type of LBT (e.g.,CAT2 LBT) to a wireless device. CAT1 LBT and CAT2 LBT may be employedfor Channel occupancy time (COT) sharing. For example, a base station (awireless device) may transmit an uplink grant (resp. uplink controlinformation) comprising a type of LBT. For example, CAT1 LBT and/or CAT2LBT in the uplink grant (or uplink control information) may indicate, toa receiving device (e.g., a base station, and/or a wireless device) totrigger COT sharing. In an example, Category 3 (CAT3, e.g. LBT withrandom back-off with a contention window of fixed size) may beimplemented. The LBT procedure may have the following procedure as oneof its components. The transmitting entity may draw a random number Nwithin a contention window. The size of the contention window may bespecified by the minimum and maximum value of N. The size of thecontention window may be fixed. The random number N may be employed inthe LBT procedure to determine the duration of time that the channel issensed to be idle before the transmitting entity transmits on thechannel. In an example, Category 4 (CAT4, e.g. LBT with random back-offwith a contention window of variable size) may be implemented. Thetransmitting entity may draw a random number N within a contentionwindow. The size of contention window may be specified by the minimumand maximum value of N. The transmitting entity may vary the size of thecontention window when drawing the random number N. The random number Nmay be used in the LBT procedure to determine the duration of time thatthe channel is sensed to be idle before the transmitting entitytransmits on the channel.

In an example, a wireless device may employ uplink (UL) LBT. The UL LBTmay be different from a downlink (DL) LBT (e.g. by using different LBTmechanisms or parameters) for example, since the NR-U UL may be based onscheduled access which affects a wireless device's channel contentionopportunities. Other considerations motivating a different UL LBTcomprise, but are not limited to, multiplexing of multiple wirelessdevices in a subframe (slot, and/or mini-slot).

In an example, DL transmission burst(s) may be a continuous (unicast,multicast, broadcast, and/or combination thereof) transmission by a basestation (e.g., to one or more wireless devices) on a carrier component(CC). UL transmission burst(s) may be a continuous transmission from oneor more wireless devices to a base station on a CC. In an example, DLtransmission burst(s) and UL transmission burst(s) on a CC in anunlicensed spectrum may be scheduled in a TDM manner over the sameunlicensed carrier. Switching between DL transmission burst(s) and ULtransmission burst(s) may require an LBT (e.g., CAT1 LBT, CAT2 LBT, CATSLBT, and/or CAT4 LBT). For example, an instant in time may be part of aDL transmission burst or an UL transmission burst.

Channel occupancy time (COT) sharing may be employed in NR-U. COTsharing may be a mechanism by which one or more wireless devices share achannel that is sensed as idle by at least one of the one or morewireless devices. For example, one or more first devices may occupy achannel via an LBT (e.g., the channel is sensed as idle based on CAT4LBT) and one or more second devices may share the channel using an LBT(e.g., 25 us LBT) within a maximum COT (MCOT) limit. For example, theMCOT limit may be given per priority class, logical channel priority,and/or wireless device specific. COT sharing may allow a concession forUL in unlicensed band. For example, a base station may transmit anuplink grant to a wireless device for a UL transmission. For example, abase station may occupy a channel and transmit, to one or more wirelessdevices a control signal indicating that the one or more wirelessdevices may use the channel. For example, the control signal maycomprise an uplink grant and/or a particular LBT type (e.g., CAT1 LBTand/or CAT2 LBT). The one or more wireless device may determine COTsharing based at least on the uplink grant and/or the particular LBTtype. The wireless device may perform UL transmission(s) with dynamicgrant and/or configured grant (e.g., Type 1, Type2, autonomous UL) witha particular LBT (e.g., CAT2 LBT such as 25 us LBT) in the configuredperiod, for example, if a COT sharing is triggered. A COT sharing may betriggered by a wireless device. For example, a wireless deviceperforming UL transmission(s) based on a configured grant (e.g., Type 1,Type2, autonomous UL) may transmit an uplink control informationindicating the COT sharing (UL-DL switching within a (M)COT). A startingtime of DL transmission(s) in the COT sharing triggered by a wirelessdevice may be indicated in one or more ways. For example, one or moreparameters in the uplink control information indicate the starting time.For example, resource configuration(s) of configured grant(s)configured/activated by a base station may indicate the starting time.For example, a base station may be allowed to perform DL transmission(s)after or in response to UL transmission(s) on the configured grant(e.g., Type 1, Type 2, and/or autonomous UL). There may be a delay(e.g., at least 4 ms) between the uplink grant and the UL transmission.The delay may be predefined, semi-statically configured (via an RRCmessage) by a base station, and/or dynamically indicated (e.g., via anuplink grant) by a base station. The delay may not be accounted in theCOT duration.

In an example, single and multiple DL to UL and UL to DL switchingwithin a shared COT may be supported. Example LBT requirements tosupport single or multiple switching points, may comprise: for a gap ofless than 16 us: no-LBT may be used; for a gap of above 16 us but doesnot exceed 25 us: one-shot LBT may be used; for single switching point,for a gap from DL transmission to UL transmission exceeds 25 us:one-shot LBT may be used; for multiple switching points, for a gap fromDL transmission to UL transmission exceeds 25 us, one-shot LBT may beused.

In an example, a signal that facilitates its detection with lowcomplexity may be useful for wireless device power saving, improvedcoexistence, spatial reuse at least within the same operator network,serving cell transmission burst acquisition, etc. In an example, a radioaccess technology (e.g., LTE and/or NR) may employ a signal comprisingat least SS/PBCH block burst set transmission. Other channels andsignals may be transmitted together as part of the signal. In anexample, the signal may be a discovery reference signal (DRS). There maybe no gap within a time span that the signal is transmitted at leastwithin a beam. In an example, a gap may be defined for beam switching.In an example, a block-interlaced based PUSCH may be employed. In anexample, the same interlace structure for PUCCH and PUSCH may be used.In an example, interlaced based PRACH may be used.

In an example, initial active DL/UL BWP may be approximately 20 MHz fora first unlicensed band, e.g., in a 5 GHz unlicensed band. An initialactive DL/UL BWP in one or more unlicensed bands may be similar (e.g.,approximately 20 MHz in a 5 GHz and/or 6 GHz unlicensed spectrum), forexample, if similar channelization is used in the one or more unlicensedbands (e.g., by a regulation).

In an example, HARQ acknowledge and negative acknowledge (A/N) for thecorresponding data may be transmitted in a shared COT (e.g., with a CAT2LBT). In some examples, the HARQ A/N may be transmitted in a separateCOT (e.g., the separate COT may require a CAT4 LBT). In an example, whenUL HARQ_feedback is transmitted on unlicensed band, a radio accesstechnology (e.g., LTE and/or NR) may support flexible triggering andmultiplexing of HARQ_feedback for one or more DL HARQ processes. HARQprocess information may be defined independent of timing (e.g., timeand/or frequency resource) of transmission. In an example, UCI on PUSCHmay carry HARQ process ID, NDI, RVID. In an example, Downlink FeedbackInformation (DFI) may be used for transmission of HARQ feedback forconfigured grant.

In an example, CBRA and CFRA may be supported on SpCell. CFRA may besupported on SCells. In an example, an RAR may be transmitted viaSpCell, e.g., non-standalone scenario. In an example, an RAR may betransmitted via SpCell and/or SCell, e.g., standalone scenario. In anexample, a predefined HARQ process ID for an RAR.

In an example, carrier aggregation between licensed band NR (PCell) andNR-U (SCell) may be supported. In an example, NR-U SCell may have bothDL and UL, or DL-only. In an example, dual connectivity between licensedband LTE (PCell) and NR-U (PSCell) may be supported. In an example,Stand-alone NR-U where all carriers are in one or more unlicensed bandsmay be supported. In an example, an NR cell with DL in unlicensed bandand UL in licensed band or vice versa may be supported. In an example,dual connectivity between licensed band NR (PCell) and NR-U (PSCell) maybe supported.

In an example, a radio access technology (e.g., LTE and/or NR) operatingbandwidth may be an integer multiple of 20 MHz, for example, if absenceof Wi-Fi cannot be guaranteed (e.g. by regulation) in an unlicensed band(e.g., 5 GHz, 6 GHZ, and/or sub-7 GHz) where the radio access technology(e.g., LTE and/or NR) is operating. In an example, a wireless device mayperformance or more LBTs in units of 20 MHz. In an example, receiverassisted LBT (e.g., RTS/CTS type mechanism) and/or on-demand receiverassisted LBT (e.g., for example receiver assisted LBT enabled only whenneeded) may be employed. In an example, techniques to enhance spatialreuse may be used.

In an operation in an unlicensed band (e.g., LTE eLAA/feLAA and/orNR-U), a wireless device may measure (averaged) received signal strengthindicator (RSSI) and/or may determine a channel occupancy (CO) of one ormore channels. For example, the wireless device may report channeloccupancy and/or RSSI measurements to the base station. It may bebeneficial to report a metric to represent channel occupancy and/ormedium contention. The channel occupancy may be defined as a portion(e.g., percentage) of time that RSSI was measured above a configuredthreshold. The RSSI and the CO measurement reports may assist the basestation to detect the hidden node and/or to achieve a load balancedchannel access to reduce the channel access collisions.

Channel congestion may cause an LBT failure. The probability ofsuccessful LBT may be increased for random access and/or for datatransmission if, for example, the wireless device selects thecell/BWP/channel with the lowest channel congestion or load. Forexample, channel occupancy aware RACH procedure may be considered toreduce LBT failure. For example, the random access backoff time for thewireless device may be adjusted based on channel conditions (e.g., basedon channel occupancy and/or RSSI measurements). For example, a basestation may (semi-statically and/or dynamically) transmit a randomaccess backoff. For example, the random access backoff may bepredefined. For example, the random access backoff may be incrementedafter or in response to one or more random access response receptionfailures corresponding to one or more random access preamble attempts.

Semi-static resource allocation of PRACH resources may be supported foran operation of a radio access technology (e.g., LTE and/or NR) in anunlicensed band. A base station may semi-statically configure a wirelessdevice with one or more random access resources, e.g., one or more timeresources, one or more frequency resources, and one or more preambles.One or more PRACH periodicities may be supported, e.g., 10, 20, 40, 60,and 160 ms. A wireless device may wait until the next configured RACHoccasion without transmitting a random access preamble, for example, ifthe wireless device determines an LBT failure, which may result in anincreased latency associated with a random access procedure for thewireless device.

There may be one or more enhancements implemented in a radio accesstechnology (e.g., LTE and/or NR) for an operation in an unlicensed band.In an example, one or more transmission opportunities for PRACH may beconfigured in time, frequency, code, and/or a combination thereof. Forexample, a base station may configure a wireless device, forcontention-free and/or contention-based RA, with one or more PRACHresources across one or more LBT sub-bands/carriers. For example, in thetime domain, a base station may configure a wireless device with one ormore PRACH resources dynamically, e.g., via DCI for connected modewireless device. For example, PRACH resources configured for a wirelessdevice may comprise one or more first PRACH resources dynamicallyconfigured (e.g., via DCI) and/or one or more second PRACH resourcesemi-statically configured (e.g., via an RRC message). For example, abase station may dynamically configure one or more PRACH resourceswithin a COT where the base station transmits one or more SSBs. Forexample, the one or more PRACH resources may be dynamically schedulede.g., via paging for idle mode wireless device and/or via DCI (or anycontrol signal) for a connected mode wireless device. For example, theone or more PRACH resources may follow one or more SSBs (e.g., DRStransmission).

A wireless device may perform LBT for accessing a channel beforetransmitting PRACH in an unlicensed band. The wireless device maytransmit the PRACH, for example, if the channel is free. The wirelessdevice may postpone the PRACH transmission, for example, if the channelis busy. A base station may reserve a time duration for the wirelessdevice before transmitting PRACH to perform LBT, e.g., an LBT gap forRACH occasion (RO). The base station may dynamically schedule RACHoccasions via a DCI. The wireless device may transmit at least onepreamble via the RACH occasions without LBT (or with performing aparticular LBT, e.g., CAT2 LBT), for example, if the gap between DL/ULswitching point (e.g., between the last DL symbol and a selected RACHoccasion) is small (e.g., less than 16 micro seconds or between 16 and25 micro seconds).

A base station may share an acquired COT with a wireless device forrandom access procedure. The base station may allow the wireless deviceto multiplex PRACH resources in UL portion of an acquired COT. Forexample, the base station may transmit, to one or more wireless device,an indication via a group-common PDCCH (GC-PDCCH) to schedule PRACHresources within the acquired COT, e.g., for connected, inactive, and/oridle mode wireless device(s). In an example, the base station maytransmit the PDCCH (e.g., GC-PDCCH) to schedule resources after one ormore SSBs (e.g., in an RMSI and/or in a DCI). In an example, thewireless device may perform one-shot (CAT2) LBT or no LBT for randomaccess preamble (Msg1) and Msg3 transmission in the COT acquired by thebase station, for example, the wireless device receives the indication.

Dynamic PRACH resource allocation may be complementary considered inaddition to the semi-statically allocated PRACH resources. In anexample, scheduling of PRACH may be triggered by DCI, e.g., a groupcommon PDCCH. The scheduling information may comprise time and frequencyresource allocation for PRACH. In an example, to reduce signalingoverhead, only parameters subject to LBT results may be configured inDCI, e.g., starting OFDM symbol and frequency resources. For example,one or more parameters comprising PRACH periodicity, preamble format,and RO number per PRACH slot may be acquired by RMSI. The DCI triggerscheme may be used for connected mode wireless devices. The DCI triggerscheme may provide robustness against LBT failures, for example byallowing PRACH resources being multiplexed in UL portion of a shared COTacquired by the base station. A GC-PDCCH may be used to schedule PRACHresources in the COT. The DCI trigger scheme may be used for idle modewireless devices. The COT may be shared between the PRACH resourcetrigger (e.g., the DCI or the DRS) and the preamble transmission. TheCOT sharing for PRACH transmission may reduce the effect of a firstwireless device performing LBT blocking a second wireless device(inter-wireless device blocking).

PRACH resources may be located inside or outside a basestation-initiated COT. PRACH transmissions may follow a first type ofLBT mechanism (e.g., CAT-2 or CAT-4 LBT) accordingly. The base stationmay indicate whether RACH occasion is located inside or outside the COTto the base station. For example, COT length indication may be signaledin a DCI that precedes the RACH occasion. For example, the DCI may beused to indicate COT reservation to cover the RACH occasions. Thewireless device may select an LBT type in accordance with theindication.

A base station may configure one or more wireless devices to share oneor more PRACH resources in unlicensed bands. The one or more wirelessdevices may block each other, for example, if the one or more wirelessdevices transmit one or more preambles without UL synchronization in thesame PRACH resource. For example, a preamble transmission time may varybetween wireless devices, for example, if the wireless devices are notUL-synchronized, and/or if the wireless devices select different valuesof backoff timers. The base station may perform an LBT to reserve PRACHresources. The PRACH resources may be within the base-station-initiatedCOT. The channel prior to the PRACH resource may be occupied by the basestation. The wireless device may assume that the channel is reserved bythe base station for PRACH transmission and may skip LBT, for examplewhen the channel prior to the PRACH resource is occupied by the servingbase station, and/or the PRACH resource is within the COT of the basestation. The base station may indicate the above information to thewireless device, for example using an initial signal or a DCI. Theinitial signal or the DCI may comprise COT sharing indication.

A random access procedure may be of high priority (e.g., for beamfailure recovery, handover) or low priority (e.g., for initial access,timing alignment, RRC reconfiguration). Channel access priority class(CAPC) for LBT type (e.g., sensing duration, contention window size,etc.) for RACH may be based on the purpose of the RACH. High priorityCAPC (e.g., shorter sensing period) may be chosen for handover and beamfailure and low priority (e.g., longer sensing period) for other usecases. For example, in the handover procedure, the PRACH transmissionmay be allowed as early as possible to avoid running into a handoverfailure/RLF condition. For example, the wireless device may performchannel access type 2 (short LBT) or type 1 (no LBT) for PRACH messages.The PRACH signal and waveform may be designed such that a type 2 or type1 LBT is allowed.

Handover in high radio frequency range with beamforming may increasemobility interruption time due to beam sweep delay. Mobilityinterruption time may refer to a time (e.g., a shortest time) durationthat the network may support during which a wireless device may notexchange user plane packets with any base station during transitions. Itmay be of interest to minimize the mobility interruption time (e.g., to0 ms). Reliability of communications may be reduced due to beamformingcharacteristics providing smaller coverage. The wireless device mayexperience very fast signal degradation when moving or rotating. Channelcondition may vary significantly in high frequency. For example,pathloss fluctuation may be tens of dB different in signal strength inbeams, or between line of sight (LoS) and non-LoS, which may result inhigher handover failure and large ping-pong rate.

Mobility performance is one of the most important performance metricsfor radio access technologies (e.g., LTE, NR). It is important toidentify handover solutions to achieve high handover performance withlow mobility interruption time (e.g., 0 ms), low latency (e.g., anaverage time between a transmission of a packet and a reception of anacknowledgement), and high reliability to provide seamless handoverexperience for the wireless device. Low mobility interruption time maybe achieved by using intra-cell beam mobility and/or addition/release ofSCell(s) for CA operation. Even though these techniques may reducemobility interruption time, there is still a need to further reducemobility interruption time in many instances (e.g., for ultra-reliablelow-latency communications (URLLC) type of service), which may requirelow end-to-end delay (e.g., 1 ms). Therefore, radio technologies mayrequire reduced handover (HO)/SCG change mobility interruption time andimproved handover reliability. The mobility enhancement may be appliedto both inter-/intra-frequency HO/SCG change. The mobility enhancementsmay not be limited to high frequency range. Solutions to reduce HO/SCGchange mobility interruption time and to improve HO reliability may alsobe beneficial to high speed trains and aerial use case where channelsituation becomes challenging in terms of HO performance.

Existing solutions to reduce mobility interruption time during HO/SCGchange may comprise: HO/SCG change with simultaneous connectivity withsource cell and target cell; make-before-break; RACH-less handover.Existing solutions to improve HO/SCG change reliability and robustnessmay comprise: conditional handover; fast handover failure recovery.

A wireless device may perform a RACH procedure during handover to obtaina timing advance (TA) value and an UL grant for PUSCH transmission(e.g., RRC reconfiguration complete message) to the target cell. In aRACH-less handover, the wireless device may skip the RACH procedureduring handover. A RACH-less handover may be used to eliminate RACHrelated latencies during HO and thus reduce mobility interruption time.RACH-less handover may be used, for example, in synchronous deployments,scenarios when the target cell TA is zero, or scenarios when the targetcell TA is the same as the source cell TA.

A wireless device configured to perform a RACH-less handover may accessthe target cell via an uplink grant pre-allocated to the wireless devicein a message (e.g., RRC reconfiguration message). The wireless devicemay monitor the PDCCH of a target cell to obtain the UL grant when, forexample, the preconfigured UL grant is not provided. However, in manydeployment scenarios RACH-less handover may not be feasible when, forexample, the target cell TA is not zero or is not the same as the sourcecell TA. This may result in increased handover latency, leading tohandover failure and/or an RLF condition. This may be especially truefor unlicensed bands, where the wireless device may perform LBT and findthe channel busy and not succeed in transmitting a preamble in thesemi-statically configured PRACH transmission occasions, resulting insignificantly increased RACH related latency.

In order to enhance random access transmission opportunities inunlicensed bands, a base station may dynamically schedule one or morefirst PRACH transmission occasions. For example, a base station mayschedule the one or more first PRACH transmission occasions during a COT(e.g., in at least one symbol of the slot) that the base stationacquires. For example, the one or more first PRACH transmissionoccasions may not be overlapped with one or more second PRACHtransmission occasions that are semi-statically configured by the basestation (e.g., via broadcast message(s)). In an existing radio accesstechnology (e.g., 4G and/or 5G), a dynamic assignment of one or morePRACH transmission occasions is not supported. In an unlicensed band, awireless device may transmit and/or receive any message (Msg1 1220, Msg2 1230, Msg 3 1230, and/or contention resolution 1250), for example,when an LBT is successful in the unlicensed band. This may result inreduced random access opportunities for the wireless devices andincreased latency in the random access procedures, leading to a longdelay for the wireless device to camp on a cell configured in theunlicensed band.

The long delay may depend on a result of LBT performed by the wirelessdevice and/or a level of congestion on the unlicensed band. Thus, thereis a need to reduce the long delay occurring in existing radio accesstechnologies. During a handover procedure in unlicensed bands, there isa need to reduce the long delay in the random access procedure to avoidhandover failure and RLF conditions.

Embodiments of the present disclosure may provide one or more mechanismsand/or parameters to enhance the random access procedure within ahandover procedure. Embodiments of the present disclosure may improve alikelihood that a random access procedure is successfully completed inan unlicensed band, resulting in an enhanced handover performance withlow mobility interruption time, low latency, and high reliability.Thereby, a battery power consumption of the wireless device may beimproved.

A wireless device may receive one or more messages from a source basestation that semi-statically configures the wireless device withinformation required to access a target cell on a target base station(e.g., the RRC reconfiguration message (the handover command)). Theinformation may comprise at least one of the following: a radio networkidentifier (e.g., a C-RNTI); system information of the target cell(e.g., SIBs); a list of candidate beams for preamble transmission to thetarget cell; PRACH resource configuration parameters (e.g., thatindicate a set of dedicated and/or common PRACH resources); and/or anassociation between PRACH resources and beams. The wireless device mayuse the information to initiate a random access procedure bytransmitting a preamble to the target base station. For example, thewireless device may transmit the preamble via a semi-static RACHoccasion configured based on PRACH resource configuration parameters inthe information. In unlicensed bands, the wireless device may perform anLBT and transmit the preamble after the LBT is successfully completed.The wireless device may not be able to transmit the preamble via thesemi-statically configured RACH occasion, for example, if the channel isoccupied and the LBT fails. The wireless device may need to wait for anext semi-statically configured RACH occasion, which will result inincreased delay in the overall handover procedure and, potentially,handover failure. Therefore, there is a need to provide additionalrandom access opportunities in the unlicensed bands.

A target base station may dynamically provide PRACH resources (e.g.,preamble, RACH occasion, beam association, etc.) to a wireless devicefor a handover procedure. For example, the target base station mayperform an LBT on a channel and, in response to the channel being idleand the LBT successfully completing, the target base station maytransmit a downlink control signal (e.g., a DCI) to the wireless deviceto dynamically schedule RACH occasions and/or trigger a random accessprocedure. In order to receive the downlink control signal, the wirelessdevice may monitor one or more PDCCH candidates in one or more controlresource sets of a target cell of the target base station. The wirelessdevice may transmit at least one preamble to the target cell in responseto receiving the downlink control signal. However, existing radio accesstechnologies (e.g., 4G and/or 5G) do not support configuration of thewireless device for monitoring the control resource set of the targetcell before a preamble transmission.

Dynamically scheduled RACH occasions may be scheduled before and/orafter semi-statically configured RACH occasions. The dynamicallyscheduled RACH occasions may be scheduled to not overlap with thesemi-statically configured RACH occasions. The dynamically scheduledRACH occasions may be determined based on the semi-statically configuredRACH occasions. For example, the dynamically scheduled RACH occasionsmay be determined by shifting the semi-statically configured RACHoccasions in the time domain and/or the frequency domain. Thedynamically scheduled RACH occasions may provide more random accessopportunities for the wireless device in unlicensed bands and, thereby,increase the likelihood of a successful LBT being performed for theunlicensed bands. This may further result in reduced mobilityinterruption time. For example, the downlink control signal may initiatea COT. For example, the downlink control signal may indicate the COTstructure information. The downlink control signal may indicate the LBTtype that the wireless device may perform to transmit a preamble.

An RRC reconfiguration message may comprise information required formonitoring and receiving the downlink control signal during a handoverprocedure (e.g., before a preamble transmission). The wireless devicemay monitor one or more configured sets of PDCCH candidates in one ormore control resource sets of the target cell, before the random accesspreamble transmission, to receive the downlink control signal thatschedules dynamic PRACH resources. The RRC reconfiguration message maycomprise a parameter indicating the presence of the downlink controlsignal.

FIG. 19 shows an example handover procedure in accordance withembodiments of the present disclosure. In FIG. 19, a source base station(BS2) may determine to handover a wireless device (UE) to a different,target base station (BS1). For example, the source base station maydetermine to handover the wireless to the target base station based onmeasurement reports received from the wireless device. The wirelessdevice may measure received power from neighboring cells and includethese measurements in the measurement reports. After determining tohandover the wireless device to the target base station, the source basestation may send a handover request message to the target base station.The target base station may perform an admission control process and mayconfirm the handover request by sending a handover requestacknowledgement, comprising an RRC reconfiguration message, to thesource base station. The source base station may forward the RRCreconfiguration message (handover command) to the wireless device. Thewireless device may be configured with parameters of one or more PRACHresources of a target cell of the target base station, and parametersrequired for monitoring and receiving a downlink control signal (e.g.,PRACH trigger signal and/or DCI). The wireless device may receive thedownlink control signal from the target cell. The wireless device maydetermine one or more random access occasions and/or a random accesspreamble based on the downlink control signal and/or the RRCreconfiguration message. The wireless device may initiate the randomaccess process for accessing the target cell. After successfullycompleting the random access process, the wireless device may transmitan RRC reconfiguration complete message to the target cell.

FIG. 20 shows example signaling that may be used during the handoverprocedure discussed above in FIG. 19 in accordance with embodiments ofthe present disclosure. After receiving the RRC reconfiguration message,the wireless device may determine at least one beam and associatedSSB(s), and the frame timing for DL synchronization. The wireless devicemay be configured by the RRC reconfiguration message to monitor one ormore sets of PDCCH candidates in one or more control resource sets toreceive the downlink control signal (e.g., PRACH trigger signal and/orDCI). After receiving the downlink control signal, the wireless devicemay transmit the preamble to the target base station via a random accessoccasion determined based on the downlink control signal to initiate arandom access. The target base station may transmit a random accessresponse (RAR) to the wireless device, indicating one or more UL grantsand/or a TA value. The wireless device may synchronize (e.g., in the ULdirection based on the TA value) to the target cell. In case ofcontention-based random access, the wireless device may transmit a Msg3to the target base station and receive a Msg4 from the target basestation (not shown in FIG. 20) to resolve the contention. The wirelessdevice may transmit an RRC reconfiguration complete message to thetarget base station to confirm successful connection and handovercompletion.

As shown in FIG. 21, the source base station may transmit to thewireless device, one or more messages (e.g., one or more RRCreconfiguration messages) in accordance with embodiments of the presentdisclosure. The one or more messages may comprise: an indicatorindicating a presence of a dynamic PRACH scheduling and/or a PRACHtrigger (e.g., via a DCI); one or more parameters of PRACH resourceconfiguration; and/or one or more parameters of monitoring for receivingthe PRACH trigger (the downlink control signal or the DCI).

One or more parameters of PRACH resource configuration may comprisecontention-free random access (CFRA) configuration and/orcontention-based random access (CBRA) configuration. The one or moreparameters of PRACH resource configuration may comprise at least one offollowing: a PRACH configuration index (e.g., prach-ConfigurationIndex);a number of PRACH transmission occasions FDMed in one time instance(e.g., msg1-FDM); an offset of a lowest PRACH transmission occasion infrequency domain with respect to PRB 0 (e.g., msg1-FrequencyStart); atarget power level at the network receiver side (e.g.,preambleReceivedTargetPower); a maximum number of preamble transmissionperformed before declaring a failure (e.g., preambleTransMax); a powerramping step for PRACH (e.g., powerRampingStep); a Msg2 (RAR) windowlength in number of slots (e.g., ra-ResponseWindow); a number of SSBsper RACH occasion (e.g., ssb-perRACH-Occasion); an index of anSSB/CSI-RS (e.g., SSB-Index and/or CSI-RS-Index); a preamble index thatthe wireless device may use to perform CFRA upon selecting the candidatebeam(s) identified by a corresponding SSB/CSI-RS (e.g.,ra-PreambleIndex); and/or a PRACH mask index for RA resource selectionassociated with the corresponding SSB/CSI-RS. The PRACH configurationindex may indicate at least one of following: a preamble format; atleast one system frame number; at least one subframe number; at leastone starting symbol; a number of PRACH slots within a subframe; and/or anumber of time-domain RACH occasions (ROs) within a PRACH slot. Thewireless device may determine a first RACH occasion (RO) based on theone or more parameters of PRACH resource configuration.

One or more parameters of monitoring for receiving the PRACH triggersignal (the downlink control signal or the DCI) may indicate: one ormore downlink control resources (CORESETs) of the target cell; a radionetwork identifier (RNTI) for the downlink control signal (the DCI); amonitoring window; and at least one time offset indicating a start ofthe monitoring window. The one or more downlink control resources maycomprise one or more resource blocks and one or more symbols, comprisingone or more monitoring occasions of the DCI. The search space setcomprising the one or more downlink control resources of the target cellmay be the search space set configured for receiving the RAR message(e.g., Type1-PDCCH common search space set configured by ra-SearchSpacefor a DCI format with CRC scrambled by a RA-RNTI or C-RNTI or TC-RNTI).The target base station may transmit the downlink control signal via abeam that the target base station transmits a reference signal (e.g.,SSB and/or CSI-RS) associated with the wireless device. The demodulationreference signal antenna port associated with the reception of thedownlink control signal via the one or more downlink control resourcesmay be quasi co-located with a first downlink reference signal (e.g.,SSB and/or CSI-RS) indicated by the one or more parameters of PRACHresource configuration. The radio network identifier of the DCI may bepredefined or configured by RRC or determined based on some parameters(e.g., RA-RNTI or C-RNTI or TC-RNTI). The size/duration of themonitoring window may be indicated in ms, or number of slots, orsymbols. The at least one time offset may be indicated in ms, or numberof slots, or symbols.

The wireless device may determine when to start to monitor the one ormore downlink control resources (e.g., search space sets) of the targetcell. A first protocol layer of the wireless device (e.g., RRC layer)processing a handover command may not control a downlink control channelmonitoring. For example, an RRC layer of a wireless device may receiveand process a handover command. A physical layer of the wireless devicemay determine a downlink control channel monitoring procedure. There maybe a need for a mechanism and/or procedure to determine, based on thehandover command, the downlink control channel monitoring.

As illustrated in FIG. 22, a wireless device may be configured tomonitor one or more downlink control resource sets (CORESETs) and/orsearch space sets (CORESET/search space sets) of a target cell. TheCORESET/search space sets of the target cell may be semi-staticallyconfigured with a period. A physical layer of the wireless device mayreceive a notification of a handover command (e.g., after reception andprocessing of an RRC reconfiguration message) from higher layers (e.g.,L3 (RRC layer)). For example, the physical layer of the wireless devicemay receive a notification of the handover command from one or morehigher layers in subframe/slot/symbol “n”, according to a downlinkreception timing of the target cell. The wireless device may synchronizeto the downlink reception timing of the target cell based on one or morereference signals transmitted by the target cell. The downlink receptiontiming of the target cell may be different than a downlink receptiontiming of the source cell, for example, due to the different distancesof the source base station and the target base station to the wirelessdevice. The physical layer of the wireless device may determine, basedon a reception time of the notification, a starting time for monitoringthe downlink control channel of the target cell. For example, thephysical layer of the wireless device may start monitoring for the PRACHtrigger signal (e.g., a DCI) in the earliest CORESET/search space set,and/or a semi-statically configured CORESET/search space set of thetarget cell, in response to a notification being received from a higherlayer (e.g., RRC layer) of the wireless device. For example, a firsttime offset “k” may be indicated by the handover command (or RRCreconfiguration message) to determine the earliest CORESET/search spaceset of the target cell. For example, a wireless device capability (e.g.,DL/UL switching time, BWP switching time, DL preparation time, and/ormeasurement gap) may indicate a second time offset “1” to determine theearliest CORESET/search space set, and/or the semi-statically configuredCORESET/search space set of the target cell. The wireless device mayemploy the first time offset “k” and/or the second time offset “1” tomonitor for the PRACH trigger signal (e.g., DCI) in a CORESET/searchspace set. For example, in FIG. 22, upon detection of a notification ofHO command in subframe/slot/symbol “n” with indication of a dynamicPRACH trigger signal (e.g., DCI) and/or configuration of monitoring forthe dynamic PRACH trigger signal (e.g., DCI), the wireless device maystart to monitor for the PRACH trigger signal in subframe/slot/symbol“n+k+1” (e.g., k>=1 may be the first time offset indicated by thehandover command (RRC reconfiguration message), and l>=1 may be thesecond time offset determined based on wireless device capability).

As shown in FIG. 23, the wireless device may start monitoring theCORESET/search space set in subframe/slot/symbol “n+k+l” according to afirst and a second pre-defined/semi-statically configured time offset(e.g., k and/or l). For example, the wireless device may startmonitoring in slot/subframe/symbol “n+k+l” of the configuredCORESET/search space set of the target cell. The wireless device maymonitor the CORESET/search space set for a duration based on apre-defined/semi-statically configured monitoring window, “W”. “W” maybe indicated in ms and/or number of slots/subframes/symbols. Thewireless device may detect a PRACH trigger signal (e.g., a DCI) in oneor more CORESET/search space set/PDCCH monitoring occasions of thetarget cell during the monitoring window. For example, as shown in FIG.23, the wireless device may receive the downlink control signal insubframe/slot/symbol “m” from the target base station. The CRC of thedownlink control signal/PRACH trigger signal (the DCI) may be scrambledby a radio network identifier indicated by the HO command (RRCreconfiguration message).

The downlink control signal (e.g., PRACH trigger signal and/or DCI) maycomprise a third time offset to indicate a dynamically scheduled RACHoccasion (RO) for the wireless device to transmit a preamble to thetarget base station. For example, the third time offset may be indicatedas “i” (i>=0), where “i” may be in ms and/or number ofslots/subframes/symbols. The value of “i” may be determined based on thewireless device capability. The value of “i” may be pre-defined. Thevalue of “i” may be configured by RRC. The downlink control signal mayalso comprise a frequency offset to indicate the dynamically scheduledRO. The wireless device may determine the dynamically scheduled RO basedon a first RACH occasion configured semi-statically by the one or moreparameters of RACH resource configuration in the HO command, and thethird time offset and/or frequency offset indicated in the downlinkcontrol signal. The small amount of information carried by the downlinkcontrol signal may result in reduced power consumption by the wirelessdevice to receive the downlink control signal.

In an example embodiment shown in FIG. 24, the wireless device mayreceive the downlink control signal from the target base station insubframe/slot/symbol “m”. The downlink control signal may indicate atime offset “i”. The wireless device may determine a firstsemi-statically configured RO based on one or more PRACH configurationparameters indicated by HO command (RRC reconfiguration message) insubframe/slot/symbol “o”. Upon reception of the downlink control signalin subframe/slot/symbol “m” indicating the time offset “i”, the wirelessdevice may assume that a second RO with same/similar configurationsas/to the first RO is dynamically scheduled in subframe/slot/symbol“m+i”. In fact, the wireless device may shift the first configured RO inthe time domain according to the third time offset indicated by thedownlink control signal. The wireless device may also shift the firstconfigured RO in the frequency domain according to the frequency offsetindicated by the downlink control signal. The wireless device maydetermine the information of the second RO based on one or more PRACHconfiguration parameters in the RRC reconfiguration message, e.g., thePRACH configuration index, the number of PRACH transmission occasionsFDMed in one time instance (msg1-FDM), the number of SSBs per RACHoccasion (e.g., ssb-perRACH-Occasion), the index of an SSB/CSI-RS (e.g.,SSB-Index and/or CSI-RS-Index), and/or the PRACH mask index associatedwith the corresponding SSB/CSI-RS. The wireless device may determine thetime (and frequency) resource of the second RO based on the receptiontime of the downlink control signal and the time (and frequency) offsetvalue indicated by the downlink control signal. The wireless maytransmit a preamble (e.g., the preamble with index indicated by the oneor more PRACH configuration parameters) to the target base station viathe second RO. The downlink control signal may indicate COT sharingindication. The wireless device may perform an LBT type, e.g., indicatedby the downlink control signal, prior to transmitting the preamble. Thewireless device may receive a RAR from the target base station after asuccessful preamble transmission. The parameters used for preambletransmission and RAR reception are determined based on the one or morePRACH configuration parameters.

The wireless device may be configured by the HO command (RRCreconfiguration message) to monitor one or more downlink controlresources (e.g., search space sets) of the target cell to receive thedownlink control signal. The HO command may comprise one or moreparameters of monitoring for receiving the control signal from thetarget base station. The one or more parameters of monitoring mayindicate the one or more downlink control resources. For example, theone or more parameters may comprise a first time offset “k” indicating afirst monitoring occasion of a CORESET/search space set comprising theone or more downlink control resources. For example, a wireless devicecapability (e.g., DL/UL switching time, BWP switching time, DLpreparation time, and/or measurement gap) may indicate a second timeoffset “1” to determine the first monitoring occasion of aCORESET/search space set comprising the one or more downlink controlresources. The wireless device may determine the first monitoringoccasion by applying the first time offset value and/or the second timeoffset value to a first (e.g., earliest, or latest) subframe/slot/symbolconfigured for reception of a reference signal (e.g., SSB/SCI-RS). Thewireless device may determine the first monitoring occasion by applyingthe first time offset value and/or the second time offset value to asecond (e.g., earliest, or latest) configured PRACHsubframe/slot/symbol. The wireless device may determine the firstmonitoring occasion by applying the first time offset value and/or thesecond time offset value to a third (e.g., earliest, or latest)subframe/slot/symbol configured for RAR reception.

In the example embodiment shown in FIG. 25, the wireless device maydetermine an SSB index (e.g., SSB #x of the target cell) insubframe/slot/symbol “n”, according to a DL timing of the target cell.The wireless device may monitor for the PRACH trigger signal (DCI) inthe CORESET/search space set of the target cell indicated by a firsttime offset “k” and/or a second time offset “1” applied tosubframe/slot/symbol “n”. For example, upon detection of the SSB #x (ora configured PRACH occasion #y) in subframe/slot/symbol “n”, thewireless device may start a monitoring window for the downlink controlsignal (e.g., PRACH trigger signal and/or DCI) in subframe/slot/symbol“n+k+l”, where “k” (k>=l) may be the first time offset indicated by thehandover command (e.g., the RRC reconfiguration message), and “l” (l>=1)may be the second time offset determined based on the wireless devicecapability. The wireless device may monitor the search space set for aduration of “W” configured for the monitoring window by the HO command(RRC reconfiguration message). The wireless device may detect thedownlink control signal in subframe/slot/symbol “m” within themonitoring window. The CRC of the downlink control signal/PRACH triggersignal (the DCI) may be scrambled by a radio network identifierindicated by the HO command (RRC reconfiguration message).

The downlink control signal may comprise one or more parameters of arandom access procedure in the target cell. For example, the downlinkcontrol signal may comprise at least one of following: a random accesspreamble index; a SS/PBCH index (or a CSI-RS index) of the target cell;a PRACH mask index that indicates a RACH occasion (RO) associated withthe SS/PBCH (or the CSI-RS) indicated by the SS/PBCH index (or theCSI-RS index) for PRACH transmission. The downlink control signal mayfurther comprise a third time offset to indicate the dynamicallyscheduled RO in the target cell. The wireless device may determine thedynamically scheduled RO based on the above parameters and one or moreparameters of PRACH resource configuration indicated by the HO command(EEC reconfiguration message), and by applying the third time offset.For example, as shown by FIG. 25, upon receiving the downlink controlsignal in subframe/slot/symbol “m” indicating the third time offset “i”,the wireless device may determine the dynamically scheduled RO insubframe/slot/symbol “m+i”. The wireless may transmit the preamble(e.g., the preamble with index indicated by the downlink control signal)to the target base station via the dynamically scheduled RO.

The wireless device may transmit a preamble via a semi-staticallyconfigured RACH occasion, for example when the wireless device may notdetect a downlink control signal for dynamic scheduling of PRACH, or forexample, when the wireless device may not perform a successful LBT toaccess the channel via a dynamically scheduled RACH occasion. Thewireless device may transmit the preamble via the dynamically scheduledRACH occasion, for example when the wireless device may not perform asuccessful LBT to access the channel via the semi-statically configuredRACH occasion. The wireless device may not expect that thesemi-statically configured RO overlap with the dynamically scheduled RO.The wireless device may successfully complete the random accessprocedure before the expiration of the HO timer (e.g., T304). Thewireless device may fall back to a CBRA using the configured randomaccess resources via HO command (RRC reconfiguration message), forexample when the wireless device is not able to successfully completethe random access procedure via the dynamically scheduled resources.

FIG. 26 is a flow diagram of an example embodiment for a wireless devicescheduled with dynamic random access channel resources during a handoverin unlicensed bands as per an aspect of the present disclosure. As shownin FIG. 26, a wireless device may receive one or more (RRC) messagesfrom a first base station, indicating a handover from a first cell ofthe first base station to a second cell of a second base station. Thewireless device may receive a DCI form the second base station. The DCImay indicate a random access channel occasion (RO). The wireless devicemay determine the RO based on the DCI. The wireless device may transmita preamble to the second base station via the RO. The wireless devicemay receive a response to the preamble from the second base station. Thewireless device may transmit, based on receiving response to thepreamble, a second message to the second base station indicating acompletion of the handover.

According to various embodiments, the one or more messages may furthercomprise a parameter indicating a presence of the DCI in the secondcell. The wireless device may determine second periodic ROs, indicatedby the one or more messages. The second periodic ROs may not comprisethe RO indicated by the DCI. The one or more messages may furtherindicate a downlink reference signal of the second cell. Demodulationreference signal antenna port associated with a reception of the DCI viaone or more downlink control channels of the second cell may be quasico-located with the downlink reference signal. The RO is associated withthe downlink reference signal. The wireless device may determine, basedon one or more time offsets, a first monitoring occasion of one or moredownlink control channels. The wireless device may start a monitoringwindow at the first monitoring occasion. The wireless device maymonitor, during the monitoring window, the one or more downlink controlchannels for the DCI identified by a radio network temporary identifier.The one or more messages may further indicate at least one of the one ormore time offsets and/or a time duration for the monitoring windowand/or the radio network temporary identifier. The first monitoringoccasion may be an earliest monitoring occasion of the one or moredownlink control channels after the one or more offsets from an end of areception of the downlink reference signal. The one or more messages maycomprise one or more parameters of random access resources of the secondcell. The one or more parameters of the random access resources maycomprise: one or more preambles comprising the preamble and/or one ormore time domain resources of the RO and/or one or more frequency domainresources of the RO. The wireless device may determine the RO based onthe one or more parameters of the random access resources indicated bythe one or more messages. The wireless device may determine the RO basedon the one or more time domain resources and/or the one or morefrequency domain resources and/or at least one offset indicated by theDCI and/or a reception timing of the DCI. The wireless device mayperform at least one channel access procedure to access a channel onwhich the preamble is transmitted, based on a type of the at least onechannel access procedure, indicated by the DCI. The wireless device maydetermine that the channel is idle before transmitting the preamble.

FIG. 27 is a flow diagram of an example embodiment for a base stationdynamically scheduling random access channel resources during a handoverin unlicensed bands as per an aspect of the present disclosure. The basestation may be a target base station. The base station may receive arequest of a handover of a wireless device from a first cell of thefirst base station to a second cell of the second base station. As shownin FIG. 27, the (e.g. target) base station may transmit to the first(e.g. source) base station a first (RRC) message indicating anacknowledgement of the request of the handover for the wireless device.The base station may transmit, to the wireless device, a DCI indicatinga random access channel occasion (RO) of the second cell. The basestation may receive a preamble from the wireless device via the RO inresponse to the DCI. The base station may transmit to the wirelessdevice a response of the preamble. The base station may receive a secondmessage from the wireless device indicating a completion of the handover(e.g. RRC reconfiguration-complete message).

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, wireless device or network nodeconfigurations, traffic load, initial system set up, packet sizes,traffic characteristics, a combination of the above, and/or the like.When the one or more criteria are met, various example embodiments maybe applied. Therefore, it may be possible to implement exampleembodiments that selectively implement disclosed protocols.

A base station may communicate with a mix of wireless devices. Wirelessdevices and/or base stations may support multiple technologies, and/ormultiple releases of the same technology. Wireless devices may have somespecific capability(ies) depending on wireless device category and/orcapability(ies). A base station may comprise multiple sectors. When thisdisclosure refers to a base station communicating with a plurality ofwireless devices, this disclosure may refer to a subset of the totalwireless devices in a coverage area. This disclosure may refer to, forexample, a plurality of wireless devices of a given LTE or 5G releasewith a given capability and in a given sector of the base station. Theplurality of wireless devices in this disclosure may refer to a selectedplurality of wireless devices, and/or a subset of total wireless devicesin a coverage area which perform according to disclosed methods, and/orthe like. There may be a plurality of base stations or a plurality ofwireless devices in a coverage area that may not comply with thedisclosed methods, for example, because those wireless devices or basestations perform based on older releases of LTE or 5G technology.

In this disclosure, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” Similarly, any termthat ends with the suffix “(s)” is to be interpreted as “at least one”and “one or more.” In this disclosure, the term “may” is to beinterpreted as “may, for example.” In other words, the term “may” isindicative that the phrase following the term “may” is an example of oneof a multitude of suitable possibilities that may, or may not, beemployed to one or more of the various embodiments.

If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on”(or equally “based at least on”) is indicative that the phrase followingthe term “based on” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “in response to” (or equally “inresponse at least to”) is indicative that the phrase following thephrase “in response to” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “depending on” (or equally “depending atleast to”) is indicative that the phrase following the phrase “dependingon” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.The phrase “employing/using” (or equally “employing/using at least”) isindicative that the phrase following the phrase “employing/using” is anexample of one of a multitude of suitable possibilities that may, or maynot, be employed to one or more of the various embodiments.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics ormay be used to implement certain actions in the device, whether thedevice is in an operational or non-operational state

In this disclosure, various embodiments are disclosed. Limitations,features, and/or elements from the disclosed example embodiments may becombined to create further embodiments within the scope of thedisclosure.

In this disclosure, parameters (or equally called, fields, orInformation elements: IEs) may comprise one or more information objects,and an information object may comprise one or more other objects. Forexample, if parameter (IE) N comprises parameter (IE) M, and parameter(IE) M comprises parameter (IE) K, and parameter (IE) K comprisesparameter (information element) J. Then, for example, N comprises K, andN comprises J. In an example embodiment, when one or more messagescomprise a plurality of parameters, it implies that a parameter in theplurality of parameters is in at least one of the one or more messages,but does not have to be in each of the one or more messages.

Furthermore, many features presented above are described as beingoptional through the use of “may” or the use of parentheses. For thesake of brevity and legibility, the present disclosure does notexplicitly recite each and every permutation that may be obtained bychoosing from the set of optional features. However, the presentdisclosure is to be interpreted as explicitly disclosing all suchpermutations. For example, a system described as having three optionalfeatures may be embodied in seven different ways, namely with just oneof the three possible features, with any two of the three possiblefeatures or with all three of the three possible features.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an element thatperforms a defined function and has a defined interface to otherelements. The modules described in this disclosure may be implemented inhardware, software in combination with hardware, firmware, wetware (i.e.hardware with a biological element) or a combination thereof, all ofwhich may be behaviorally equivalent. For example, modules may beimplemented as a software routine written in a computer languageconfigured to be executed by a hardware machine (such as C, C++,Fortran, Java, Basic, Matlab or the like) or a modeling/simulationprogram such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript.Additionally, it may be possible to implement modules using physicalhardware that incorporates discrete or programmable analog, digitaland/or quantum hardware. Examples of programmable hardware comprise:computers, microcontrollers, microprocessors, application-specificintegrated circuits (ASICs); field programmable gate arrays (FPGAs); andcomplex programmable logic devices (CPLDs). Computers, microcontrollersand microprocessors are programmed using languages such as assembly, C,C++ or the like. FPGAs, ASICs and CPLDs are often programmed usinghardware description languages (HDL) such as VHSIC hardware descriptionlanguage (VHDL) or Verilog that configure connections between internalhardware modules with lesser functionality on a programmable device. Theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the scope. In fact, after reading the abovedescription, it will be apparent to one skilled in the relevant art(s)how to implement alternative embodiments. Thus, the present embodimentsshould not be limited by any of the above described exemplaryembodiments.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112. Claims that do not expressly include the phrase “means for”or “step for” are not to be interpreted under 35 U.S.C. 112.

What is claimed is:
 1. A method comprising: receiving, by a wirelessdevice from a first base station, one or more messages indicating: ahandover from a first cell of the first base station to a second cell ofa second base station; a time duration of a monitoring window; and atime offset of the monitoring window; and starting, based on the timeoffset, the monitoring window in a slot comprising a monitoring occasionof a downlink control channel of the second cell; receiving, via atleast one monitoring occasion of the downlink control channel and duringthe time duration of the monitoring window, a downlink controlinformation (DCI) from the second cell, wherein the DCI indicates arandom-access-channel occasion (RO) of the second cell; and transmittinga preamble to the second cell via the RO.
 2. The method of claim 1,wherein the one or more messages comprise a parameter indicating apresence of the DCI in the second cell.
 3. The method of claim 1,further comprising determining periodic ROs indicated by the one or moremessages, wherein the periodic ROs do not comprise the RO indicated bythe DCI.
 4. The method of claim 1, wherein: the one or more messagesfurther indicate a downlink reference signal of the second cell; ademodulation reference signal antenna port, associated with thereception of the DCI via one or more downlink control channels of thesecond cell, is quasi co-located with the downlink reference signal; andthe RO is associated with the downlink reference signal.
 5. The methodof claim 1, wherein the DCI is identified by a radio network temporaryidentifier.
 6. The method of claim 5, wherein the one or more messagesfurther indicate: the radio network temporary identifier.
 7. The methodof claim 5, wherein the monitoring occasion is an earliest monitoringoccasion of the downlink control channel after the offset from an end ofa reception of a downlink reference signal of the second cell.
 8. Themethod of claim 1, wherein: the one or more messages comprise one ormore parameters of random access resources of the second cell, the oneor more parameters comprising: one or more preambles comprising thepreamble; one or more time domain resources of the RO; and one or morefrequency domain resources of the RO; and wherein the RO is determinedfurther based on the one or more parameters of the random accessresources indicated by the one or more messages.
 9. The method of claim8, wherein the determining the RO comprises determining the RO based on:the one or more time domain resources; the one or more frequency domainresources; at least one offset indicated by the DCI; and a receptiontiming of the DCI.
 10. The method of claim 1, further comprising:performing, based on a type of channel access procedure, at least onechannel access procedure to access a channel on which the preamble istransmitted, wherein the type is indicated by the DCI; and determiningthat the channel is idle before transmitting the preamble.
 11. Awireless device comprising: one or more processors; and memory storinginstructions that, when executed by the one or more processors, causethe wireless device to: receive, from a first base station, one or moremessages indicating: a handover from a first cell of the first basestation to a second cell of a second base station; a time duration of amonitoring window; and a time offset of the monitoring window; andstart, based on the time offset, the monitoring window in a slotcomprising a monitoring occasion of a downlink control channel of thesecond cell; receive, via at least one monitoring occasion of thedownlink control channel and during the time duration of the monitoringwindow, a downlink control information (DCI) from the second cell,wherein the DCI indicates a random-access-channel occasion (RO) of thesecond cell; and transmit a preamble to the second cell via the RO. 12.The wireless device of claim 11, wherein the one or more messagescomprise a parameter indicating a presence of the DCI in the secondcell.
 13. The wireless device of claim 11, wherein the instructionsfurther cause the wireless device to determine periodic ROs indicated bythe one or more messages, and wherein the periodic ROs do not comprisethe RO indicated by the DCI.
 14. The wireless device of claim 11,wherein: the one or more messages further indicate a downlink referencesignal of the second cell; a demodulation reference signal antenna port,associated with the reception of the DCI via one or more downlinkcontrol channels of the second cell, is quasi co-located with thedownlink reference signal; and the RO is associated with the downlinkreference signal.
 15. The wireless device of claim 11, wherein the DCIis identified by a radio network temporary identifier.
 16. The wirelessdevice of claim 15, wherein the one or more messages further indicatethe radio network temporary identifier.
 17. The wireless device of claim15, wherein the monitoring occasion is an earliest monitoring occasionof the downlink control channel after the offset from an end of areception of a downlink reference signal of the second cell.
 18. Thewireless device of claim 11, wherein: the one or more messages compriseone or more parameters of random access resources of the second cell,the one or more parameters comprising: one or more preambles comprisingthe preamble; one or more time domain resources of the RO; and one ormore frequency domain resources of the RO; and wherein the RO isdetermined further based on the one or more parameters of the randomaccess resources indicated by the one or more messages.
 19. The wirelessdevice of claim 18, wherein the instructions further cause the wirelessdevice to determine the RO based on: the one or more time domainresources; the one or more frequency domain resources; at least oneoffset indicated by the DCI; and a reception timing of the DCI.
 20. Asystem comprising: a first base station; a second base station; and awireless device comprising: one or more processors; and a memory storinginstructions that, when executed by the one or more processors, causethe wireless device to: receive, from the first base station, one ormore messages indicating: a handover from a first cell of the first basestation to a second cell of the second base station; a time duration ofa monitoring window; and a time offset of the monitoring window; andstart, based on the time offset, the monitoring window in a slotcomprising a monitoring occasion of a downlink control channel of thesecond cell; receive, via at least one monitoring occasion of thedownlink control channel and during the time duration of the monitoringwindow, a downlink control information (DCI) from the second cell,wherein the DCI indicates a random-access-channel occasion (RO) of thesecond cell; and transmit a preamble to the second cell via the RO.